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1
Wraback, E. M., E. Landi e W. B. Manchester. "Using the Cartwheel CME to Predict Off-limb Observations of CMEs for New and Upcoming UV and EUV Spectrometers". Astrophysical Journal 974, n. 1 (1 ottobre 2024): 32. http://dx.doi.org/10.3847/1538-4357/ad6d58.
Testo completoAbstract (sommario):
Abstract Coronal mass ejections (CMEs) expel multithermal, magnetized plasma from the Sun, and when directed toward Earth, can cause extensive damage to space and ground-based electronics. To better understand the triggering, acceleration, and evolution of CMEs, it is critical to study CME plasma properties close to the Sun. High-resolution ultraviolet and extreme ultraviolet (UV-EUV) spectroscopy can give the most detailed plasma diagnostics of CMEs in the low solar corona. Unfortunately, very few spectrally resolved observations of CMEs in the low solar corona exist. However, with the recent launch of the Spectral Imaging of the Coronal Environment on board Solar Orbiter and the upcoming missions, including the EUV High-Throughput Solar Telescope (EUVST) on Solar-C and the Multi-slit Solar Explorer (MUSE), we will have the opportunity to obtain unprecedented, spectrally resolved CME observations. Using the only full EUV spectral observation of a CME by the Hinode/EUV Imaging Spectrometer, we predict the spectra that SPICE, EUVST, and MUSE are expected to observe during an off-limb CME eruption to investigate the diagnostic capabilities of each instrument. Finally, we provide a list of density-sensitive and temperature-sensitive ratios for CME plasma diagnostics along with the expected spectral atlas for each instrument to facilitate observing sequence planning.
2
Golub, Leon, Peter Cheimets, Edward E. DeLuca, Chad A. Madsen, Katharine K. Reeves, Jenna Samra, Sabrina Savage, Amy Winebarger e Alexander R. Bruccoleri. "EUV imaging and spectroscopy for improved space weather forecasting". Journal of Space Weather and Space Climate 10 (2020): 37. http://dx.doi.org/10.1051/swsc/2020040.
Testo completoAbstract (sommario):
Accurate predictions of harmful space weather effects are mandatory for the protection of astronauts and other assets in space, whether in Earth or lunar orbit, in transit between solar system objects, or on the surface of other planetary bodies. Because the corona is multithermal (i.e., structured not only in space but also in temperature), wavelength-separated data provide crucial information that is not available to imaging methods that integrate over temperature. The extreme ultraviolet (EUV) wavelengths enable us to focus directly on high temperature coronal plasma associated with solar flares, coronal mass ejections (CMEs), and shocked material without being overwhelmed by intensity from the solar disk. Both wide-field imaging and spectroscopic observations of the solar corona taken from a variety of orbits (e.g., Earth, L1, or L5) using suitably-chosen EUV instrumentation offer the possibility of addressing two major goals to enhance our space weather prediction capability, namely: (1) Improve our understanding of the coronal conditions that control the opening and closing of the corona to the heliosphere and consequent solar wind streams, and (2) Improve our understanding of the physical processes that control the early evolution of CMEs and the formation of shocks, from the solar surface out into the extended corona.
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Kuzin, S. V., S. A. Bogachev, I. A. Zhitnik, A. A. Pertsov, A. P. Ignatiev, A. M. Mitrofanov, V. A. Slemzin, S. V. Shestov, N. K. Sukhodrev e O. I. Bugaenko. "TESIS experiment on EUV imaging spectroscopy of the Sun". Advances in Space Research 43, n. 6 (marzo 2009): 1001–6. http://dx.doi.org/10.1016/j.asr.2008.10.021.
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Verma, M., C. Denker, A. Diercke, C. Kuckein, H. Balthasar, E. Dineva, I. Kontogiannis, P. S. Pal e M. Sobotka. "High-resolution spectroscopy of a surge in an emerging flux region". Astronomy & Astrophysics 639 (luglio 2020): A19. http://dx.doi.org/10.1051/0004-6361/201936762.
Testo completoAbstract (sommario):
Aims. The regular pattern of quiet-Sun magnetic fields was disturbed by newly emerging magnetic flux, which led a day later to two homologous surges after renewed flux emergence, affecting all atmospheric layers. Hence, simultaneous observations in different atmospheric heights are needed to understand the interaction of rising flux tubes with the surrounding plasma, in particular by exploiting the important diagnostic capabilities provided by the strong chromospheric Hα line regarding morphology and energetic processes in active regions. Methods. A newly emerged active region NOAA 12722 was observed with the Vacuum Tower Telescope (VTT) at Observatorio del Teide, Tenerife, Spain, on 11 September 2018. High spectral resolution observations using the echelle spectrograph in the chromospheric Hαλ6562.8 Å line were obtained in the early growth phase. Noise-stripped Hα line profiles yield maps of line-core and bisector velocities, which were contrasted with velocities inferred from Cloud Model inversions. A high-resolution imaging system recorded simultaneously broad- and narrowband Hα context images. The Solar Dynamics Observatory provided additional continuum images, line-of-sight (LOS) magnetograms, and UV and extreme UV (EUV) images, which link the different solar atmospheric layers. Results. The active region started as a bipolar region with continuous flux emergence when a new flux system emerged in the leading part during the VTT observations, resulting in two homologous surges. While flux cancellation at the base of the surges provided the energy for ejecting the cool plasma, strong proper motions of the leading pores changed the magnetic field topology making the region susceptible to surging. Despite the surge activity in the leading part, an arch filament system in the trailing part of the old flux remained stable. Thus, stable and violently expelled mass-loaded ascending magnetic structures can coexist in close proximity. Investigating the height dependence of LOS velocities revealed the existence of neighboring strong up- and downflows. However, downflows occur with a time lag. The opacity of the ejected cool plasma decreases with distance from the base of the surge, while the speed of the ejecta increases. The location at which the surge becomes invisible in Hα corresponds to the interface where the surge brightens in He IIλ304 Å. Broad-shouldered and dual-lobed Hα profiles suggests accelerated or decelerated and highly structured LOS plasma flows. Significantly broadened Hα profiles imply significant heating at the base of the surges, which is also supported by bright kernels in UV and EUV images uncovered by swaying motions of dark fibrils at the base of the surges. Conclusions. The interaction of newly emerging flux with pre-existing flux concentrations of a young, diffuse active region provided suitable conditions for two homologous surges. High-resolution spectroscopy revealed broadened and dual-lobed Hα profiles tracing accelerated or decelerated flows of cool plasma along the multi-threaded structure of the surge.
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Vievering, Juliana T., Angelos Vourlidas e Säm Krucker. "Unraveling the Origins of an Extreme Solar Eruptive Event with Hard X-Ray Imaging Spectroscopy". Astrophysical Journal 972, n. 1 (23 agosto 2024): 48. http://dx.doi.org/10.3847/1538-4357/ad57b7.
Testo completoAbstract (sommario):
Abstract Hard X-ray (HXR) observations are crucial for understanding the initiation and evolution of solar eruptive events, as they provide a key signature of flare-accelerated electrons and heated plasma. The potential of high-cadence HXR imaging for deciphering the erupting structure, however, has not received adequate attention in an era of extreme ultraviolet (EUV) imaging abundance. An extreme solar eruptive event on 2022 September 5 observed on the solar far side by both Parker Solar Probe and Solar Orbiter provides the opportunity to showcase the power of HXR imaging in the absence of high-cadence EUV imaging. We investigate the evolution of flare energy release through HXR timing, imaging, and spectral analyses using data from the Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter. STIX provides the highest cadence imaging of the energy release sites for this far-side event and offers crucial insight into the nature of energy release, timing of flare particle acceleration, and evolution of the acceleration efficiency. We find that this is a two-phase eruptive event, rather than two distinct eruptions, as has been previously suggested. The eruption begins with an initial peak in flare emission on one side of the active region (AR), marking the rise/destabilization of a loop system followed by notable episodes of energy release across the AR and an eruptive phase associated with a very fast coronal mass ejection, type III radio bursts, and solar energetic particles. We demonstrate that high-cadence HXR imaging spectroscopy is indispensable for understanding the formation of powerful, space-weather relevant eruptions.
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de Castro, Ana I. Gómez, e Martin A. Barstow. "Joint Discussion 4 UV astronomy: stars from birth to death". Proceedings of the International Astronomical Union 2, n. 14 (agosto 2006): 169–94. http://dx.doi.org/10.1017/s1743921307010083.
Testo completoAbstract (sommario):
AbstractThe scientific program is presented as well a the abstracts of the contributions. An extended account is published in “The Ultraviolet Universe: stars from birth to death” (Ed. Gómez de Castro) published by the Editorial Complutense de Madrid (UCM), that can be accessed by electronic format through the website of the Network for UV Astronomy (www.ucm.es/info/nuva).There are five telescopes currently in orbit that have a UV capability of some description. At the moment, only FUSE provides any medium- to high-resolution spectroscopic capability. GALEX, the XMM UV-Optical Telescope (UVOT) and the Swift. UVOT mainly delivers broad-band imaging, but with some low-resolution spectroscopy using grisms. The primary UV spectroscopic capability of HST was lost when the Space Telescope Imaging Spectrograph failed in 2004, but UV imaging is still available with the HST-WFPC2 and HST-ACS instruments.With the expected limited lifetime of sl FUSE, UV spectroscopy will be effectively unavailable in the short-term future. Even if a servicing mission of HST does go ahead, to install COS and repair STIS, the availability of high-resolution spectroscopy well into the next decade will not have been addressed. Therefore, it is important to develop new missions to complement and follow on from the legacy of FUSE and HST, as well as the smaller imaging/low resolution spectroscopy facilities. This contribution presents an outline of the UV projects, some of which are already approved for flight, while others are still at the proposal/study stage of their development.This contribution outlines the main results from Joint Discussion 04 held during the IAU General Assembly in Prague, August 2006, concerning the rationale behind the needs of the astronomical community, in particular the stellar astrophysics community, for new UV instrumentation. Recent results from UV observations were presented and future science goals were laid out. These goals will lay the framework for future mission planning.
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Verhoeve, P. "UV/optical imaging spectroscopy with cryogenic detectors". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 444, n. 1-2 (aprile 2000): 435–40. http://dx.doi.org/10.1016/s0168-9002(99)01420-5.
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Brown, Robert L., Anthony R. Kerr, A. Richard Thompson e Frederic R. Schwab. "High-Resolution Imaging Spectroscopy at Terahertz Frequencies". International Astronomical Union Colloquium 123 (1990): 509–15. http://dx.doi.org/10.1017/s0252921100077575.
Testo completoAbstract (sommario):
AbstractHISAT, a multi-element heterodyne interferometer attached to Space Station Freedom, will provide spectroscopic images with unprecedented detail of those submillimeter lines of C,O and C+ which are critical diagnostics of UV excitation in the Galaxy. With the arcsecond angular resolution achievable from the space station, HISAT will reveal: – The distribution of sources of ultraviolet radiation in the Galaxy;–The effective temperature of the UV radiation as a function of galactocentric radius;– The chemical and isotopic enhancement of atomic carbon and oxygen with galactic radius;– The propagation of UV radiation in molecular clouds and its stimulative, or inhibitive, effect on star formation;– The density structure, dumpiness or fragmentation, of molecular clouds throughout the Galaxy. HISAT has been selected by NASA for a concept-phase study.
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Sciortino, F., N. T. Howard, R. Reksoatmodjo, A. R. Foster, J. W. Hughes, E. S. Marmar, M. A. Miller et al. "Experimental inference of neutral and impurity transport in Alcator C-Mod using high-resolution x-ray and ultra-violet spectra". Nuclear Fusion 61, n. 12 (18 novembre 2021): 126060. http://dx.doi.org/10.1088/1741-4326/ac32f2.
Testo completoAbstract (sommario):
Abstract We present experimental inferences of cross-field impurity transport coefficients for AlcatorC-Mod plasmas without edge-localized modes, leveraging a novel forward model for the entire Ca K α spectrum, including satellite lines within the spectral range, to compare to high-resolution x-ray imaging crystal spectroscopy (XICS). These measurements are complemented by extreme ultra-violet (EUV) spectroscopy that constrains transport closer to the edge. Using new atomic data sets for both XICS and EUV analysis has enabled consideration of line ratios across both spectral ranges and has increased the accuracy of inferred transport coefficients. Inclusion of charge exchange between edge thermal neutrals and impurities is shown to be extremely important in C-Mod pedestals. Atomic D neutral densities from experimental D Ly α measurements at the midplane are compared to SOLPS-ITER simulations, finding good agreement. Bayesian inferences of impurity transport coefficients are presented for L-, EDA H-, and I-mode discharges, making use of the Aurora package for forward modeling and combining our spectroscopic constraints. Experimentally inferred diffusion profiles are found to match turbulent transport models at midradius within uncertainties, using both quasilinear gyro-fluid TGLF SAT-1 and nonlinear ion-scale gyrokinetic CGYRO simulations. Significant discrepancies in convection are observed in some cases, suggesting difficulties in predictions of flat or hollow impurity profiles.
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Brooks, David H., Miho Janvier, Deborah Baker, Harry P. Warren, Frédéric Auchère, Mats Carlsson, Andrzej Fludra et al. "Plasma Composition Measurements in an Active Region from Solar Orbiter/SPICE and Hinode/EIS". Astrophysical Journal 940, n. 1 (1 novembre 2022): 66. http://dx.doi.org/10.3847/1538-4357/ac9b0b.
Testo completoAbstract (sommario):
Abstract A key goal of the Solar Orbiter mission is to connect elemental abundance measurements of the solar wind enveloping the spacecraft with extreme-UV (EUV) spectroscopic observations of their solar sources, but this is not an easy exercise. Observations from previous missions have revealed a highly complex picture of spatial and temporal variations of elemental abundances in the solar corona. We have used coordinated observations from Hinode and Solar Orbiter to attempt new abundance measurements with the Spectral Imaging of the Coronal Environment (SPICE) instrument, and benchmark them against standard analyses from the EUV Imaging Spectrometer (EIS). We use observations of several solar features in active region (AR) 12781 taken from an Earth-facing view by EIS on 2020 November 10, and SPICE data obtained one week later on 2020 November 17, when the AR had rotated into the Solar Orbiter field of view. We identify a range of spectral lines that are useful for determining the transition region and low-coronal-temperature structure with SPICE, and demonstrate that SPICE measurements are able to differentiate between photospheric and coronal magnesium/neon abundances. The combination of SPICE and EIS is able to establish the atmospheric composition structure of a fan loop/outflow area at the AR edge. We also discuss the problem of resolving the degree of elemental fractionation with SPICE, which is more challenging without further constraints on the temperature structure, and comment on what that can tell us about the sources of the solar wind and solar energetic particles.
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Zhang, Jiale, Bin Chen, Sijie Yu, Hui Tian, Yuqian Wei, Hechao Chen, Guangyu Tan, Yingjie Luo e Xingyao Chen. "Implications for Additional Plasma Heating Driving the Extreme-ultraviolet Late Phase of a Solar Flare with Microwave Imaging Spectroscopy". Astrophysical Journal 932, n. 1 (1 giugno 2022): 53. http://dx.doi.org/10.3847/1538-4357/ac6ce3.
Testo completoAbstract (sommario):
Abstract Extreme-ultraviolet late phase (ELP) refers to the second extreme-ultraviolet (EUV) radiation enhancement observed in certain solar flares, which usually occurs tens of minutes to several hours after the peak of soft X-ray emission. The coronal loop system that hosts the ELP emission is often different from the main flaring arcade, and the enhanced EUV emission therein may imply an additional heating process. However, the origin of the ELP remains rather unclear. Here we present the analysis of a C1.4 flare that features such an ELP, which is also observed in microwave wavelengths by the Expanded Owens Valley Solar Array. Similar to the case of the ELP, we find a gradual microwave enhancement that occurs about 3 minutes after the main impulsive phase microwave peaks. Radio sources coincide with both foot points of the ELP loops and spectral fits on the time-varying microwave spectra demonstrate a clear deviation of the electron distribution from the Maxwellian case, which could result from injected nonthermal electrons or nonuniform heating to the footpoint plasma. We further point out that the delayed microwave enhancement suggests the presence of an additional heating process, which could be responsible for the evaporation of heated plasma that fills the ELP loops, producing the prolonged ELP emission.
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Sachkov, M., B. Shustov, I. Savanov e A. I. Gómez de Castro. "WSO-UV project for high-resolution spectroscopy and imaging". Astronomische Nachrichten 335, n. 1 (gennaio 2014): 46–50. http://dx.doi.org/10.1002/asna.201312015.
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Hufziger, Kyle T., Sergei V. Bykov e Sanford A. Asher. "Ultraviolet Raman Wide-Field Hyperspectral Imaging Spectrometer for Standoff Trace Explosive Detection". Applied Spectroscopy 71, n. 2 (9 dicembre 2016): 173–85. http://dx.doi.org/10.1177/0003702816680002.
Testo completoAbstract (sommario):
We constructed the first deep ultraviolet (UV) Raman standoff wide-field imaging spectrometer. Our novel deep UV imaging spectrometer utilizes a photonic crystal to select Raman spectral regions for detection. The photonic crystal is composed of highly charged, monodisperse 35.5 ± 2.9 nm silica nanoparticles that self-assemble in solution to produce a face centered cubic crystalline colloidal array that Bragg diffracts a narrow ∼1.0 nm full width at half-maximum (FWHM) UV spectral region. We utilize this photonic crystal to select and image two different spectral regions containing resonance Raman bands of pentaerythritol tetranitrate (PETN) and NH4NO3 (AN). These two deep UV Raman spectral regions diffracted were selected by angle tuning the photonic crystal. We utilized this imaging spectrometer to measure 229 nm excited UV Raman images containing ∼10–1000 µg/cm2 samples of solid PETN and AN on aluminum surfaces at 2.3 m standoff distances. We estimate detection limits of ∼1 µg/cm2 for PETN and AN films under these experimental conditions.
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Hickson, Paul, e J. B. Hutchings. "Resolved imaging and spectroscopy of QSOs". Symposium - International Astronomical Union 119 (1986): 117–19. http://dx.doi.org/10.1017/s0074180900152428.
Testo completoAbstract (sommario):
We have obtained direct images and off-nuclear spectra for five QSOs having a wide range of radio, optical and X-ray luminosity. Four objects show absorption features identified with stars in a host galaxy, and off-nuclear changes in emission line wavelengths. All objects show off-nuclear changes in continuum coulour, and in emission line intensities and ratios. The radio loud objects have more luminous galaxies, strong and extended [OII] and [OIII], and UV-bright nuclei. They tend to have luminous nuclei, high nuclear to galaxy luminosity ratio, and blue host galaxies. This paper is a brief summary of results that will appear in more detail elsewhere.
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Al Ktash, Mohammad, Mona Stefanakis, Tim Englert, Maryam S. L. Drechsel, Jan Stiedl, Simon Green, Timo Jacob et al. "UV Hyperspectral Imaging as Process Analytical Tool for the Characterization of Oxide Layers and Copper States on Direct Bonded Copper". Sensors 21, n. 21 (4 novembre 2021): 7332. http://dx.doi.org/10.3390/s21217332.
Testo completoAbstract (sommario):
Hyperspectral imaging and reflectance spectroscopy in the range from 200–380 nm were used to rapidly detect and characterize copper oxidation states and their layer thicknesses on direct bonded copper in a non-destructive way. Single-point UV reflectance spectroscopy, as a well-established method, was utilized to compare the quality of the hyperspectral imaging results. For the laterally resolved measurements of the copper surfaces an UV hyperspectral imaging setup based on a pushbroom imager was used. Six different types of direct bonded copper were studied. Each type had a different oxide layer thickness and was analyzed by depth profiling using X-ray photoelectron spectroscopy. In total, 28 samples were measured to develop multivariate models to characterize and predict the oxide layer thicknesses. The principal component analysis models (PCA) enabled a general differentiation between the sample types on the first two PCs with 100.0% and 96% explained variance for UV spectroscopy and hyperspectral imaging, respectively. Partial least squares regression (PLS-R) models showed reliable performance with R2c = 0.94 and 0.94 and RMSEC = 1.64 nm and 1.76 nm, respectively. The developed in-line prototype system combined with multivariate data modeling shows high potential for further development of this technique towards real large-scale processes.
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Pinet, P. C. "Spectroscopic Imaging of Solid Planetary Surfaces". International Astronomical Union Colloquium 149 (1995): 294–97. http://dx.doi.org/10.1017/s0252921100023186.
Testo completoAbstract (sommario):
Seen from Sirius through the eye of the telescope, our inner solar system would easily fit within one CCD-pixel. The purpose of the present paper is: i) to provide with a general overview of the use of imaging or 3D-spectroscopy for the study of the solid planetary surfaces, ii) to demonstrate that the analysis of 3D spectroscopic data on the basis of spectral mixture modelling permits to describe the subpixel spectral variability related to mineralogy of the planetary solid surfaces. In the following, a few cases are discussed concerning the remote sensing investigation in the UV-VIS-nIR domain of the lunar, terrestrial and martian surfaces, documented by means of multispectral or hyperspectral data, produced by telescopic, airborne or orbital imaging spectroscopic techniques.
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Zhu 朱, Yingjie 英杰, Shadia R. Habbal, Adalbert Ding, Bryan Yamashiro, Enrico Landi, Benjamin Boe, Sage Constantinou e Michael Nassir. "Spectroscopic Observations of the Solar Corona during the 2017 August 21 Total Solar Eclipse: Comparison of Spectral Line Widths and Doppler Shifts between Open and Closed Magnetic Structures". Astrophysical Journal 966, n. 1 (30 aprile 2024): 122. http://dx.doi.org/10.3847/1538-4357/ad3424.
Testo completoAbstract (sommario):
Abstract The spectroscopic observations presented here were acquired during the 2017 August 21 total solar eclipse (TSE) with a three-channel partially multiplexed imaging spectrometer operating at extremely high orders (>50). The 4 R ⊙ extent of the slit in the north–south direction scanned the corona starting from the central meridian out to approximately 1.0 R ⊙ off the east limb throughout totality. The line widths and Doppler shifts of the Fe x (637.4 nm) and Fe xiv (530.3 nm) emission lines, characteristic of 1.1 × 106 K and 1.8 × 106 K electron temperatures, respectively, varied across the different coronal structures intercepted by the slit. Fe xiv was the dominant emission in the closed fields of an active region and the base of a streamer, with relatively constant 20–30 km s−1 line widths independent of the height. In contrast, Fe x emission exhibited broader (>40 km s−1) line widths in open fields, which increased with height, in particular in the polar coronal hole. Inferences of line widths and Doppler shifts were consistent with extreme ultraviolet (EUV) observations from the Hinode/EUV Imaging Spectrograph, as well as with the near-infrared Fe xiii 1074 nm line observed by Coronal Multichannel Polarimeter. The differences in the spectral line widths between distinct coronal structures are interpreted as an indication of the predominance of wave heating in open structures versus localized heating in closed structures. This study underscores the unparalleled advantages and the enormous potential of TSE spectroscopy in measuring line widths simultaneously in open and closed fields at high altitudes, with minimal exposure times, stray light levels, and instrumental widths.
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Pronti, Lucilla, Anna Candida Felici, Matthieu Ménager, Cathy Vieillescazes e Mario Piacentini. "Spectral Behavior of White Pigment Mixtures Using Reflectance, Ultraviolet—Fluorescence Spectroscopy, and Multispectral Imaging". Applied Spectroscopy 71, n. 12 (21 luglio 2017): 2616–25. http://dx.doi.org/10.1177/0003702817717969.
Testo completoAbstract (sommario):
Reflectance spectroscopy, ultraviolet (UV)—fluorescence spectroscopy, and multispectral imaging have been widely employed for pigment identification on paintings. From ancient times to the present, lead white, zinc white, and titanium white have been the most important white pigments used for paintings and they are used as pigment markers for dating a work of art. The spectral behavior of these pigments is reported in several scientific papers and websites, but those of their mixtures are quite unknown. We present a combined nondestructive approach for identifying mixtures of lead white, zinc white, and titanium white as powder and dispersed in two different binder media (egg yolk and linseed oil) by using reflectance spectroscopy, spectrofluorimetry, multispectral reflectance and UV-fluorescence imaging. We propose a novel approach for mapping the presence of white pigments in paintings by false color images obtained from multispectral reflectance and UV-fluorescence images. We found that the presence of lead white mixed with either zinc white or titanium white is highly detectable. Zinc white mixed with lead white or titanium white can be identified due to its UV-fluorescence emission, whereas titanium white in association with lead white or zinc white is distinguishable by its reflectance spectral features. In most cases, the UV-fluorescence analyses also permit the recognition of the binder media in which the pigments are dispersed.
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Pronti, Lucilla, Giuseppe Capobianco, Margherita Vendittelli, Anna Candida Felici, Silvia Serranti e Giuseppe Bonifazi. "Optimized Method for Mapping Inorganic Pigments by Means of Multispectral Imaging Combined with Hyperspectral Spectroscopy for the Study of Vincenzo Pasqualoni’s Wall Painting at the Basilica of S. Nicola in Carcere in Rome". Minerals 11, n. 8 (2 agosto 2021): 839. http://dx.doi.org/10.3390/min11080839.
Testo completoAbstract (sommario):
Multispectral imaging is a preliminary screening technique for the study of paintings. Although it permits the identification of several mineral pigments by their spectral behavior, it is considered less performing concerning hyperspectral imaging, since a limited number of wavelengths are selected. In this work, we propose an optimized method to map the distribution of the mineral pigments used by Vincenzo Pasqualoni for his wall painting placed at the Basilica of S. Nicola in Carcere in Rome, combining UV/VIS/NIR reflectance spectroscopy and multispectral imaging. The first method (UV/VIS/NIR reflectance spectroscopy) allowed us to characterize pigment layers with a high spectral resolution; the second method (UV/VIS/NIR multispectral imaging) permitted the evaluation of the pigment distribution by utilizing a restricted number of wavelengths. Combining the results obtained from both devices was possible to obtain a distribution map of a pictorial layer with a high accuracy level of pigment recognition. The method involved the joint use of point-by-point hyperspectral spectroscopy and Principal Component Analysis (PCA) to identify the pigments in the color palette and evaluate the possibility to discriminate all the pigments recognized, using a minor number of wavelengths acquired through the multispectral imaging system. Finally, the distribution and the spectral difference of the different pigments recognized in the multispectral images, (in this case: red ochre, yellow ochre, orpiment, cobalt blue-based pigments, ultramarine and chrome green) were shown through PCA false-color images.
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Kuhn, Jonas, Ulrich Platt, Nicole Bobrowski e Thomas Wagner. "Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range". Atmospheric Measurement Techniques 12, n. 1 (1 febbraio 2019): 735–47. http://dx.doi.org/10.5194/amt-12-735-2019.
Testo completoAbstract (sommario):
Abstract. Many processes in the lower atmosphere including transport, turbulent mixing and chemical conversions happen on timescales of the order of seconds (e.g. at point sources). Remote sensing of atmospheric trace gases in the UV and visible spectral range (UV–Vis) commonly uses dispersive spectroscopy (e.g. differential optical absorption spectroscopy, DOAS). The recorded spectra allow for the direct identification, separation and quantification of narrow-band absorption of trace gases. However, these techniques are typically limited to a single viewing direction and limited by the light throughput of the spectrometer set-up. While two-dimensional imaging is possible by spatial scanning, the temporal resolution remains poor (often several minutes per image). Therefore, processes on timescales of seconds cannot be directly resolved by state-of-the-art dispersive methods. We investigate the application of Fabry–Pérot interferometers (FPIs) for the optical remote sensing of atmospheric trace gases in the UV–Vis spectral range. By choosing a FPI transmission spectrum, which is optimised to correlate with narrow-band (ideally periodic) absorption structures of the target trace gas, column densities of the trace gas can be determined with a sensitivity and selectivity comparable to dispersive spectroscopy, using only a small number of spectral channels (FPI tuning settings). Different from dispersive optical elements, the FPI can be implemented in full-frame imaging set-ups (cameras), which can reach high spatio-temporal resolution. In principle, FPI correlation spectroscopy can be applied for any trace gas with distinct absorption structures in the UV–Vis range. We present calculations for the application of FPI correlation spectroscopy to SO2, BrO and NO2 for exemplary measurement scenarios. In addition to high sensitivity and selectivity we find that the spatio temporal resolution of FPI correlation spectroscopy can be more than 2 orders of magnitude higher than state-of-the-art DOAS measurements. As proof of concept we built a 1-pixel prototype implementing the technique for SO2 in the UV. Good agreement with our calculations and conventional measurement techniques is demonstrated and no cross sensitivities to other trace gases are observed.
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Nordberg, Markus, e Lars Landström. "UV Raman chemical imaging using compressed sensing". Analyst 144, n. 5 (2019): 1513–18. http://dx.doi.org/10.1039/c9an00056a.
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Grava, C., W. R. Pryor, P. D. Feldman, K. D. Retherford, G. R. Gladstone e T. K. Greathouse. "LRO/LAMP study of the interstellar medium via the HeI 58.4 nm resonance line". Astronomy & Astrophysics 616 (agosto 2018): A159. http://dx.doi.org/10.1051/0004-6361/201731555.
Testo completoAbstract (sommario):
Context. Recent measurements by IBEX and detailed modeling have changed our understanding of the flow of the interstellar medium through the solar system. In particular, a time dependence of the direction of the interstellar medium flow has been proposed, and a new population of helium atoms, called the “warm breeze”, has been discovered. Aims. We aim to constrain the structure of the interstellar medium close to the downwind focusing cone using the sensitive LAMP FUV/EUV imaging spectrograph onboard the Lunar Reconnaissance Orbiter. Methods. We measured the brightness of the emission line from interstellar helium atoms resonantly scattering solar photons at 58.4 nm (HeI) and compare it to our “modified cold model” of interstellar HeI sky brightness as a function of ecliptic latitude and longitude. Additionally, we compared LAMP observations to a model with time-dependent inflow direction and a model of the brightness of the “warm breeze”, to see if they can be distinguished by LAMP. Results. We find that the LAMP observations agree within error bars to our “modified cold model”, which in turn is consistent with the latest interstellar helium flow parameters found with IBEX. Our model can therefore be applied to other UV spectroscopic observations of the interstellar helium. However, LAMP observations cannot distinguish between our model and a model with a different inflow direction, since the latter has negligible effect on the 2D brightness of the interstellar HeI emission line. For the same reason, LAMP could not detect the effect of the “warm breeze”. We note a discrepancy between solar irradiances measured by TIMED/SEE and those measured by SDO/EVE. We recommend using values from SDO/EVE. Finally, we derive a value of LAMP sensitivity at the EUV wavelength (58.4 nm) of 0.485 ± 0.014 Hz/Rayleigh. Conclusions. These measurements pave the way to observations of the interstellar wind from lunar orbit.
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Thierry-Jebali, Nicolas, Chihiro Kawahara, Tetsuya Miyazawa, Hidekazu Tsuchida e Tsunenobu Kimoto. "Identification of Stacking Faults by UV Photoluminescence Imaging Spectroscopy on Thick, Lightly-Doped n-Type 4°-off 4H-SiC Epilayers". Materials Science Forum 821-823 (giugno 2015): 323–26. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.323.
Testo completoAbstract (sommario):
This work reports on description and application of a new Photoluminescence (PL) Imaging technique for in-grown stacking fault (SF) characterization and identification on 4H-SiC epilayers. The purpose of this technique is to make a spectroscopic picture from a collection of PL imaging picture taken at different output wavelengths in order to both display the shape and an approximation of the maximum PL intensity wavelength at room temperature (RT) of the characterized SF. This is why we called this technique “PL Imaging Spectroscopy”. Five types of SFs have been observed and compared to PL spectra collected at RT and 10K.
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Gabrieli, F., K. A. Dooley, M. Facini e J. K. Delaney. "Near-UV to mid-IR reflectance imaging spectroscopy of paintings on the macroscale". Science Advances 5, n. 8 (agosto 2019): eaaw7794. http://dx.doi.org/10.1126/sciadv.aaw7794.
Testo completoAbstract (sommario):
Broad spectral range reflectance imaging spectroscopy (BR-RIS) from the near UV through the mid–infrared (IR) (350 to 25,000 nm or 28,571 to 400 cm−1) was investigated as an imaging modality to provide maps of organic and inorganic artists’ materials in paintings. While visible–to–near-IR (NIR) reflectance and elemental x-ray fluorescence (XRF) imaging spectroscopies have been used for in situ mapping, each method alone is insufficient for robust identification. Combining the two improves results but requires complex data processing. To test BR-RIS, image cubes from early Italian Renaissance illuminated manuscripts were acquired using two spectrometers. Maps of pigments, including trace minerals associated with mined azurite, and their associated binding media were made. BR-RIS has a more straightforward analysis approach as implemented here than visible-to-NIR, mid-IR, or XRF imaging spectroscopy alone and offers the largest amount of macroscale information for mapping artists’ materials by comparison.
25
Gupta, Girjesh R., e Sushree S. Nayak. "Spectroscopic and imaging observations of transient hot and cool loops by IRIS and SDO". Monthly Notices of the Royal Astronomical Society 512, n. 3 (31 marzo 2022): 3149–62. http://dx.doi.org/10.1093/mnras/stac657.
Testo completoAbstract (sommario):
ABSTRACT Coronal loops are the basic building blocks of the solar atmosphere and are observed on various length scales. However, their formation mechanism is still unclear. In this paper, we present spectroscopic and imaging observations of small-scale transients and the subsequent formation of transient loops. For this purpose, we have utilized the multiwavelength observations recorded by the Atmospheric Imaging Assembly (AIA) and the Interface Region Imaging Spectrograph (IRIS) slit-jaw imager (SJI), along with spectroscopic measurements provided by IRIS. For the photospheric magnetic field data, we obtained line-of-sight magnetogram data provided by the Helioseismic and Magnetic Imager (HMI). Small-scale transients are simultaneously observed with several EUV and UV passbands of AIA and IRIS/SJI. The HMI magnetogram provides evidence of negative flux cancellations beneath these transients. Differential emission measure (DEM) analysis shows that one of the transients attains temperatures up to 8 MK whereas another one only reaches 0.4 MK. These transients further lead to the formation of small-scale loops with similar temperature distributions, thus termed hot and cool loops respectively. During the course of events, the IRIS slit was rastering the region and thus provided spectroscopic measurements at both transients and associated loops. This enabled us to perform in-depth investigations of the hot and cool loops. Using a density-sensitive O iv line pair, we obtained average electron densities along the hot and cool loops to be 1011.2 and 1010.8 cm−3 respectively. Energy estimates suggest that flux cancellation could easily power the hot transient, while it is insufficient for the cool transient. Lifetime estimates and magnetic field extrapolation suggest the presence of small-scale and fine structures within these loops. The results provide crucial ingredients for the physics of loop formation and the thermodynamics involved.
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Gómez de Castro, Ana I., Boris Shustov e Mikhail Sachkov. "The World Space Observatory - Ultraviolet (WSO-UV) Space Telescope; Status Update in 2013". Acta Polytechnica CTU Proceedings 1, n. 1 (4 dicembre 2014): 298–302. http://dx.doi.org/10.14311/app.2014.01.0298.
Testo completoAbstract (sommario):
This is a short primer and a brief update on the status of the World Space Observatory-Ultraviolet (WSO-UV) project dated in May 2013. WSO-UV is a 170m primary space telescope equipped for ultraviolet imaging and spectroscopy that will be operational in 2017 hosting an open science program for the world-wide scientic community.
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Bianchi, Luciana, David Thilker, Armando Gil de Paz e Barry Madore. "Extended UV Disk (XUV-disk) Galaxies". Proceedings of the International Astronomical Union 2, S235 (agosto 2006): 301. http://dx.doi.org/10.1017/s1743921306006661.
Testo completoAbstract (sommario):
AbstractMotivated by the GALEX discovery of recent star formation in outermost regions of M83 and NGC4625, we have investigated the nature of the XUV disks with follow-up high resolution imaging and spectroscopy, and attempted to detect them at other wavelengths (IR, Hα). We searched for additional XUV-disk galaxies in the local universe, in order to quantify the incidence of the XUV-disk phenomenon, infer the causes of such extended star formation (SF), and place these systems in the context of disk galaxy evolution.
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Sadykov, V. M., A. G. Kosovichev, I. N. Sharykin, I. V. Zimovets e S. Vargas Dominguez. "Initiation and chromospheric effects of a M1.0 class solar flare from high-resolution multi-wavelength observations". Proceedings of the International Astronomical Union 12, S327 (ottobre 2016): 103–8. http://dx.doi.org/10.1017/s1743921317003994.
Testo completoAbstract (sommario):
AbstractInitiation and development of a M 1.0 class flare of June 12, 2014, was observed by space and ground-based telescopes, including EUV and X-ray imaging spectroscopy by IRIS and RHESSI, and high-resolution optical imaging by 1.6 m New Solar Telescope (NST). Analyzing the NST data, we found small-scale loop-like structures in the region of the magnetic field Polarity Inversion Line (PIL), the emergence and interaction of which caused photospheric brightenings temporarily coinciding with hard X-ray impulses. Detailed studies of the PIL region reveal signatures of photospheric plasma downflows and dissipation of electric currents. The reconstructed magnetic field topology shows a bundle of lines connecting the PIL region with the flare ribbons which were places of chromospheric evaporation observed by IRIS. The observations suggest a scenario with the primary energy release processes located in the low atmospheric layers of the PIL, energizing the overlying large-scale magnetic structure and causing “gentle” chromospheric evaporation.
29
Namratha, Bathula. "Study on Hyper Spectral Imaging". International Journal for Research in Applied Science and Engineering Technology 9, n. VI (20 giugno 2021): 2017–21. http://dx.doi.org/10.22214/ijraset.2021.35403.
Testo completoAbstract (sommario):
Spectroscopy deals with how light behave in the target and recognize materials bases on their different spectral signatures. Spectrum describes the amount and range of radiation that is emitted, reflected or transmitted from the target. Hyper spectral data acquisition and exploitation by providing imaging sensors and software solutions covering hundreds of spectral bands from UV-VIS to SWIS is used to observe Earth, atmospheric science, space situation awareness etc. The work focuses primarily on hyper spectral imaging, data acquisition methods, Image resolution improvement strategies.
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Caldwell, Joshua D., Laurent Lombez, Amaury Delamarre, Jean Francois Guillemoles, Brice Bourgoin, Brett A. Hull e Marc Verhaegen. "Luminescence Imaging of Extended Defects in SiC via Hyperspectral Imaging". Materials Science Forum 717-720 (maggio 2012): 403–6. http://dx.doi.org/10.4028/www.scientific.net/msf.717-720.403.
Testo completoAbstract (sommario):
Over the past decade, improvements in silicon carbide growth and materials has led to the development of commercialized unipolar devices such as Schottky diodes and MOSFETs, however, much work remains to realizing the goal of wide-scale commercialization of both unipolar and bipolar devices such as pin diodes or IGBTs, for high applications requiring high powers, operating in elevated temperatures or radiation environments or for many fast switching applications. Despite the great strides that have been made in reducing extended and point defect densities during this period, such defects still remain and with the push to lower off-cut angle substrates are in many cases seeing increases in prevalence. Thus, spectroscopic and imaging techniques for locating and identifying these defects are in high demand. Luminescence imaging and spectroscopy have both been utilized heavily in such work, yet simultaneously obtaining corresponding spectroscopic and spatial information from such defects is problematic. Here we report on hyperspectral imaging of electroluminescence from SiC pin diodes, whereby a stack of luminescence images are collected over a wide spectral range (400-900 nm), thereby providing the ability to both image distinct features and identify their corresponding spectral properties. This process is also equally applicable to collecting either photo- or electroluminescence from other materials or devices emitting in either the UV-Vis or NIR spectral range, as well as to reflectance, transmission or other imaging techniques.
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Hutchings, J. B., e S. G. Neff. "Morphology and Spectroscopy of Markarian 231". Symposium - International Astronomical Union 121 (1987): 399–401. http://dx.doi.org/10.1017/s007418090015541x.
Testo completoAbstract (sommario):
Deep optical imaging of Mkn 231 reveals twin (tidal?) tails, a linear nuclear feature at green wavelengths, and a very blue region 4 arcsec south of the nucleus. Much of the central part of the galaxy is red, but there are complex areas of blue luminosity outside this, and a sharp edge to the luminosity at a distance of ~16 arcsec from the centre. Overall, the host galaxy appears to have a normal optical luminosity and blue colour (B-R ~0.7) despite being one of the most luminous galaxies known in the infrared. Radio emission in the system is extended on one side on a similar scale to the optical tails, but shows no detailed correspondence with optical structure; in particular there is no radio counterpart to the optical ‘jet’. Examination of IUE archival data indicate that the UV flux is very weak and the UV spectrum is peculiar for a Seyfert galaxy. The UV observations provide evidence for considerable nuclear extinction in the system, in accordance with previously published optical and infrared work, but the UV extinction is unlike Galactic absorption and may be more similar to that seen in the LMC. Recent optical spectra of Mkn 231 show changes in both the emission line spectrum and in the strong broad absorption lines (BAL), compared with previously published observations. This places strong limitations on the size of the nuclear continuum source. We suggest that Mkn 221 is a recently merged system which is currently undergoing star-formation, and discuss the connection with BAL QSOs.
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Smeland, Knut Arne, Kristian Hovde Liland, Jakub Sandak, Anna Sandak, Lone Ross Gobakken, Thomas Kringlebotn Thiis e Ingunn Burud. "Near Infrared Hyperspectral Imaging in Transmission Mode: Assessing the Weathering of Thin Wood Samples". Journal of Near Infrared Spectroscopy 24, n. 6 (1 gennaio 2016): 595–604. http://dx.doi.org/10.1255/jnirs.1253.
Testo completoAbstract (sommario):
Untreated wooden surfaces degrade when exposed to natural weathering. In this study thin wood samples were studied for weather degradation effects utilising a hyperspectral camera in the near infrared wavelength range in transmission mode. Several sets of samples were exposed outdoors for time intervals from 0 days to 21 days, and one set of samples was exposed to ultraviolet (UV) radiation in a laboratory chamber. Spectra of earlywood and latewood were extracted from the hyperspectral image cubes using a principal component analysis-based masking algorithm. The degradation was modelled as a function of UV solar radiation with four regression techniques, partial least squares, principal component regression, Ridge regression and Tikhonov regression. It was found that all the techniques yielded robust prediction models on this dataset. The result from the study is a first step towards a weather dose model determined by temperature and moisture content on the wooden surface in addition to the solar radiation.
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Xie, Chuanqi, e Weidong Zhou. "A Review of Recent Advances for the Detection of Biological, Chemical, and Physical Hazards in Foodstuffs Using Spectral Imaging Techniques". Foods 12, n. 11 (5 giugno 2023): 2266. http://dx.doi.org/10.3390/foods12112266.
Testo completoAbstract (sommario):
Traditional methods for detecting foodstuff hazards are time-consuming, inefficient, and destructive. Spectral imaging techniques have been proven to overcome these disadvantages in detecting foodstuff hazards. Compared with traditional methods, spectral imaging could also increase the throughput and frequency of detection. This study reviewed the techniques used to detect biological, chemical, and physical hazards in foodstuffs including ultraviolet, visible and near-infrared (UV-Vis-NIR) spectroscopy, terahertz (THz) spectroscopy, hyperspectral imaging, and Raman spectroscopy. The advantages and disadvantages of these techniques were discussed and compared. The latest studies regarding machine learning algorithms for detecting foodstuff hazards were also summarized. It can be found that spectral imaging techniques are useful in the detection of foodstuff hazards. Thus, this review provides updated information regarding the spectral imaging techniques that can be used by food industries and as a foundation for further studies.
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Rauw, Gregor, Karel A. van der Hucht, Rolf Mewe, Manuel Güdel, Jean-Marie Vreux, Eric Gosset, Werner Schmutz e Ian R. Stevens. "On the perspectives of using XMM to study fundamental parameters of early-type stars". Symposium - International Astronomical Union 193 (1999): 90–91. http://dx.doi.org/10.1017/s0074180900205093.
Testo completoAbstract (sommario):
Although substantial progress has been achieved since the discovery of X-ray emission from early-type stars with the EINSTEIN satellite, several crucial aspects of this phenomenon are still not fully understood. Considerable breakthroughs in this field are expected from observations with the X-ray Multi-Mirror satellite (XMM) due for launch in early 2000. XMM is the second cornerstone mission of the ESA Horizon 2000 science programme (see Lumb et al. 1996 and references therein for an overall description of the satellite). XMM offers a large effective area over a wide range of energies and its instrumentation provides simultaneously non-dispersive spectroscopic imaging (EPIC - European Photon Imaging Camera), medium-resolution dispersive spectroscopy (RGS - Reflection Grating Spectrometer) and optical-UV imaging (OM - Optical Monitor).
35
يسر رائد محمد e وليد صلاح عبد الوهاب. "Studying The Fluorescence Resonance Energy Transfer between Fluorescein and Rhodamine B in an aqueous solution". journal of the college of basic education 28, n. 117 (31 dicembre 2022): 1–12. http://dx.doi.org/10.35950/cbej.v28i117.9066.
Testo completoAbstract (sommario):
The energy transfer of fluorescence resonance in aqueous solution was studied between two organic dyes, Fluorescein and Rhodamine B. Both dyes were found in solution as monomers, according to spectroscopic studies. Energy transfer was observed in fluorescence resonance imaging solutions containing fluorescein and rhodamine B. with different concentrations of the acceptor RhB dye in the range of (1.5×10-5 M to 3.5×10-5M). Studies using Both UV–vis absorption and fluorescence spectroscopy demonstrated that the two dyes, when dissolved in solution, appear largely as monomers.
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Koochakzaei, Alireza, Ali Nemati Babaylou e Behrooz Jelodarian Bidgoli. "Identification of Coatings on Persian Lacquer Papier Mache Penboxes by Fourier Transform Infrared Spectroscopy and Luminescence Imaging". Heritage 4, n. 3 (24 agosto 2021): 1962–69. http://dx.doi.org/10.3390/heritage4030111.
Testo completoAbstract (sommario):
In this study, Fourier transform infrared spectroscopy (FTIR) and luminescence imaging were used to identify the coatings of seven Persian lacquer papier mache penboxes, of which two were contemporary, one was from the Pahlavi era, and four belonged to the Qajar era. First, FTIR was used to identify the nature of the coating. Then, UV-induced visible luminescence imaging at the spectral ranges of 420–680 nm (UVL), 425–495 nm (UVIBL), and 615–645 nm (UVIRL) was performed for further examination. The FTIR results showed that the coatings were made of alkyd resin, oil-resin varnish (Kaman oil), and shellac. In UV-induced visible luminescence images, synthetic alkyd resin showed no fluorescence, which made it distinguishable from the natural organic coatings. While it is slightly challenging to differentiate Kaman oil from shellac based on FTIR results, these two coatings can be easily distinguished by their fluorescence in UVL and UVIBL images. The results suggest that the combined use of spectroscopy and spectral imaging methods can provide substantial information about the organic coatings of historical objects.
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Galarza, Vanessa C., Donald R. Garnett e You-Hua Chu. "Imaging and spectroscopy of the LMC He II nebula N 44C and its ionizing star". Symposium - International Astronomical Union 193 (1999): 480–81. http://dx.doi.org/10.1017/s0074180900206074.
Testo completoAbstract (sommario):
We present results from new HST imaging and spectroscopy of the peculiar Large Magellanic Cloud H II region N 44C and its ionizing star. While this nebula exhibits strong He II recombination emission, the source of the He+ ionizing photons has not been found. The UV spectrum of the ionizing star suggests an approximate spectral class of 07–08; the UV Si IV, He II, and N IV features do not show P-Cygni profiles, indicating that the ionizing star is not a supergiant. No companion star has yet been detected. Ground-based and HST optical spectroscopy of the ionized gas shows that the nebular abundances of C, N, O and He are not anomalous relative to other LMC H II regions, suggesting that no previous WR/SN companion has disappeared. Echelle spectroscopy has also ruled out the presence of high velocity shocked gas. Deep ROSAT imaging shows no X-ray point source in this location. The “fossil X-ray binary” hypothesis of Pakull & Motch (1989) remains the best explanation for the ionization of this nebula; however, convincing evidence for this hypothesis remains elusive.
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Polyanichko, Alexander, e Helmut Wieser. "Structural organization of DNA–protein complexes of chromatin studied by vibrational and electronic circular dichroism". Spectroscopy 24, n. 3-4 (2010): 239–44. http://dx.doi.org/10.1155/2010/658374.
Testo completoAbstract (sommario):
Structure and functioning of chromatin is determined by interactions of DNA with numerous nuclear proteins. The most abundant and yet not completely understood non-histone chromosomal proteins are those belonging to a High Mobility Group (HMG) namely HMGB1. The interplay of this protein on DNA with linker histone H1 and other proteins determines both structure and functioning of the chromatin. A combination of UV and IR absorption and circular dichroism (CD) spectroscopy was applied to investigate the structure and formation of large supramolecular DNA–protein complexes. This combination of techniques was used to overcome limitations of UV-CD (ECD) spectroscopy due to considerable light scattering in such solutions. Based on the analysis of FTIR and UV circular dichroism spectra and AFM imaging the interaction of DNA with high-mobility group non-histone chromatin protein HMGB1 and linker histone H1 was studied.
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Mohandoss, Sonaimuthu, Jeyachandran Sivakamavalli, Baskaralingam Vaseeharan e Thambusamy Stalin. "Fluorometric sensing of Pb2+and CrO42−ions through host–guest inclusion for human lung cancer live cell imaging". RSC Advances 5, n. 123 (2015): 101802–18. http://dx.doi.org/10.1039/c5ra17910f.
Testo completo
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Schnopper, Herbert W. "XSPECT: A Telescope/Spectrometer System on SPECTRUM RÖNTGEN GAMMA". International Astronomical Union Colloquium 115 (1990): 307–17. http://dx.doi.org/10.1017/s0252921100012513.
Testo completoAbstract (sommario):
AbstractThe SPECTRUM RÖNTGEN-GAMMA mission is being developed by the Babakin Center (BC) together with the Space Research Institute (IKI) of the Academy of Sciences, USSR and is scheduled for launch in 1993. Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from the EUV through gamma rays with particular emphasis on the study of extragalactic objects. The Danish Space Research Institute (DSRI) BC and IKI share the responsibility for the preparation of the XSPECT system. Two thin foil telescopes which are conical shell approximations to Wolter 1 geometry, each with an aperture of 60 cm and a focal length of 8 m, are designed to have a half-power width of less than 2 arcmin and will have collecting areas of 1700 and 1200 cm at 2 and 8 keV, respectively. Images and spectra will be recorded with position sensitive proportional counters with good spectral resolution. An objective Bragg crystal panel, placed in front of one of the telescopes, will make high resolution spectroscopic studies (E/ΔE ~103) of point- and extended sources. Other instruments are under consideration.
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Ocaña, Luis, Carlos Montes, Sara González-Pérez, Benjamín González-Díaz e Elena Llarena. "Characterization of a New Low Temperature Encapsulation Method with Ethylene-Vinyl Acetate under UV Irradiation for Perovskite Solar Cells". Applied Sciences 12, n. 10 (21 maggio 2022): 5228. http://dx.doi.org/10.3390/app12105228.
Testo completoAbstract (sommario):
In this work, the performance of a new ethylene-vinyl acetate-based low temperature encapsulation method, conceived to protect perovskite samples from UV irradiation in ambient conditions, has been analyzed. To this purpose, perovskite samples consisting of a set of MAPbI3 (CH3NH3PbI3) films and MAPbI3 with an ETL layer were deposited over glass substrates by spin-coating techniques and encapsulated using the new method. The samples were subjected to an UV lamp or to full solar irradiation in ambient conditions, with a relative humidity of 60–80%. Microscope imaging, spectroscopic ellipsometry and Fourier-transform infrared spectroscopy (FTIR) techniques were applied to analyze the samples. The obtained results indicate UV energy is responsible for the degradation of the perovskite layer. Thus, the cut-UV characteristics of the EVA encapsulate acts as an efficient barrier, allowing the laminated samples to remain stable above 350 h under full solar irradiation compared with non-encapsulated samples. In addition, the FTIR results reveal perovskite degradation caused by UV light. To extend the study to encompass whole PSCs, simulations were carried out using the software SCAPS-1D, where the non-encapsulated devices present a short-circuit current reduction after exposure to UV irradiation, while the encapsulated ones maintained their efficiency.
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Chen, Zhe, Zhaoyang Ding, Guangya Zhang, Leilei Tian e Xuanjun Zhang. "Construction of Thermo-Responsive Elastin-Like Polypeptides (ELPs)-Aggregation-Induced-Emission (AIE) Conjugates for Temperature Sensing". Molecules 23, n. 7 (14 luglio 2018): 1725. http://dx.doi.org/10.3390/molecules23071725.
Testo completoAbstract (sommario):
In this work, an aggregation-induced emission (AIE) molecule (tetraphenylethene derivative, TPE-COOH) was conjugated to elastin-like polypeptides (ELPs40) via an amide bond to form ELPs40-TPE. The successful synthesis of ELPs40-TPE was confirmed by Circular Dichroism spectroscopy, gel electrophoresis, UV-vis absorption, and fluorescence emission spectroscopy. ELPs40-TPE possessed both amphiphilicity and the features of an AIE, and the fluorescence intensity was dependent on the local temperature. The Hela cells imaging indicated that ELPs40-TPE has great potential for bio-imaging applications because of its advantages of high fluorescence intensity, good water-solubility, and remarkable biocompatibility.
43
Wei, Yuqian, Bin Chen, Sijie Yu, Haimin Wang, Ju Jing e Dale E. Gary. "Coronal Magnetic Field Measurements along a Partially Erupting Filament in a Solar Flare". Astrophysical Journal 923, n. 2 (1 dicembre 2021): 213. http://dx.doi.org/10.3847/1538-4357/ac2f99.
Testo completoAbstract (sommario):
Abstract Magnetic flux ropes are the centerpiece of solar eruptions. Direct measurements for the magnetic field of flux ropes are crucial for understanding the triggering and energy release processes, yet they remain heretofore elusive. Here we report microwave imaging spectroscopy observations of an M1.4-class solar flare that occurred on 2017 September 6, using data obtained by the Expanded Owens Valley Solar Array. This flare event is associated with a partial eruption of a twisted filament observed in Hα by the Goode Solar Telescope at the Big Bear Solar Observatory. The extreme ultraviolet (EUV) and X-ray signatures of the event are generally consistent with the standard scenario of eruptive flares, with the presence of double flare ribbons connected by a bright flare arcade. Intriguingly, this partial eruption event features a microwave counterpart, whose spatial and temporal evolution closely follow the filament seen in Hα and EUV. The spectral properties of the microwave source are consistent with nonthermal gyrosynchrotron radiation. Using spatially resolved microwave spectral analysis, we derive the magnetic field strength along the filament spine, which ranges from 600 to 1400 Gauss from its apex to the legs. The results agree well with the nonlinear force-free magnetic model extrapolated from the preflare photospheric magnetogram. We conclude that the microwave counterpart of the erupting filament is likely due to flare-accelerated electrons injected into the filament-hosting magnetic flux rope cavity following the newly reconnected magnetic field lines.
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Gull, Maude, Daniel R. Weisz, Peter Senchyna, Nathan R. Sandford, Yumi Choi, Anna F. McLeod, Kareem El-Badry et al. "A Panchromatic Study of Massive Stars in the Extremely Metal-poor Local Group Dwarf Galaxy Leo A*". Astrophysical Journal 941, n. 2 (1 dicembre 2022): 206. http://dx.doi.org/10.3847/1538-4357/aca295.
Testo completoAbstract (sommario):
Abstract We characterize massive stars (M > 8 M ⊙) in the nearby (D ∼ 0.8 Mpc) extremely metal-poor (Z ∼ 5% Z ⊙) galaxy Leo A using Hubble Space Telescope ultraviolet (UV), optical, and near-infrared (NIR) imaging along with Keck/Low-Resolution Imaging Spectrograph and MMT/Binospec optical spectroscopy for 18 main-sequence OB stars. We find that: (a) 12 of our 18 stars show emission lines, despite not being associated with an H ii region, suggestive of stellar activity (e.g., mass loss, accretion, binary star interaction), which is consistent with previous predictions of enhanced activity at low metallicity; (b) six are Be stars, which are the first to be spectroscopically studied at such low metallicity—these Be stars have unusual panchromatic SEDs; (c) for stars well fit by the TLUSTY nonlocal thermodynamic equilibrium models, the photometric and spectroscopic values of log ( T eff ) and log ( g ) agree to within ∼0.01 dex and ∼0.18 dex, respectively, indicating that near-UV/optical/NIR imaging can be used to reliably characterize massive (M ∼ 8–30 M ⊙) main-sequence star properties relative to optical spectroscopy; (d) the properties of the most-massive stars in H II regions are consistent with constraints from previous nebular emission line studies; and (e) 13 stars with M > 8M ⊙ are >40 pc from a known star cluster or H II region. Our sample comprises ∼50% of all known massive stars at Z ≲ 10% Z ⊙with derived stellar parameters, high-quality optical spectra, and panchromatic photometry.
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Villaseñor-Aguilar, Marcos-Jesús, José-Alfredo Padilla-Medina, José-Enrique Botello-Álvarez, Micael-Gerardo Bravo-Sánchez, Juan Prado-Olivares, Alejandro Espinosa-Calderon e Alejandro-Israel Barranco-Gutiérrez. "Current Status of Optical Systems for Measuring Lycopene Content in Fruits: Review". Applied Sciences 11, n. 19 (8 ottobre 2021): 9332. http://dx.doi.org/10.3390/app11199332.
Testo completoAbstract (sommario):
Optical systems are used for analysing the internal composition and the external properties in food. The measurement of the lycopene content in fruits and vegetables is important because of its benefits to human health. Lycopene prevents cardiovascular diseases, cataracts, cancer, osteoporosis, male infertility, and peritonitis. Among the optical systems focused on the estimation and identification of lycopene molecule are high-performance liquid chromatography (HPLC), the colorimeter, infrared near NIR spectroscopy, UV-VIS spectroscopy, Raman spectroscopy, and the systems of multispectral imaging (MSI) and hyperspectral imaging (HSI). The main objective of this paper is to present a review of the current state of optical systems used to measure lycopene in fruits. It also reports important factors to be considered in order to improve the design and implementation of those optical systems. Finally, it was observed that measurements with HPLC and spectrophotometry present the best results but use toxic solvents and require specialized personnel for their use. Moreover, another widely used technique is colorimetry, which correlates the lycopene content using color descriptors, typically those of CIELAB. Likewise, it was identified that spectroscopic techniques and multispectral images are gaining importance because they are fast and non-invasive.
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Babini, Agnese, Phil Green, Sony George e Jon Yngve Hardeberg. "Comparison of Hyperspectral Imaging and Fiber-Optic Reflectance Spectroscopy for Reflectance and Transmittance Measurements of Colored Glass". Heritage 5, n. 3 (23 giugno 2022): 1401–19. http://dx.doi.org/10.3390/heritage5030073.
Testo completoAbstract (sommario):
The work presented in this paper is part of a wider research project, which aims at documenting and analyzing stained glass windows by means of hyperspectral imaging. This technique shares some similarities with UV-VIS-IR spectroscopy, as they both provide spectral information; however, spectral imaging has the additional advantage of providing spatial information, since a spectrum can be collected in each pixel of the image. Compared to UV-VIS-IR spectroscopy, spectral imaging has rarely been used for the investigation of stained glass windows. One of the objectives of this paper is, thus, to compare the performance of these two instruments to validate the results of hyperspectral imaging. The second objective is to evaluate the potential of analyzing colored-glass pieces in reflectance modality and compare the results with those obtained in transmittance, in order to highlight the differences and similarities between the two approaches. The geometry of the systems and the backing material for the glass, as well as the characteristics of the glass pieces, are discussed. L*a*b* values obtained from the spectra, as well as the calculated color difference ΔE00, are provided, to show the degree of agreement between the instruments and the two measurement modalities.
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Singh, Avanendra, Kartik Senapati, Karuna Kar Nanda e Pratap K. Sahoo. "Strong Red Luminescent Twin ZnO Nanorods for Nano-thermometry Application". MRS Advances 1, n. 13 (2016): 869–74. http://dx.doi.org/10.1557/adv.2016.162.
Testo completoAbstract (sommario):
ABSTRACTTwo segments of horizontally grown crystalline ZnO nanorods (NRs) connected with an amorphous layer have been successfully and reproducibly synthesized using one-step hydrothermal technique by controlling the growth rate. The confocal photoluminescence (PL) imaging and spectroscopy of twin ZnO NRs at different temperatures shows intense red emission with comparably week UV emission. The strong red emission from the twin NRs is a consequence of structural imperfections. Both UV and red bands showed signatures of strong temperature dependent exciton-phonon scattering. Using the intensity ratio of the UV and red emissions, we show that the individual ZnO NRs can be used as highly sensitive cryogenic temperature sensors below ∼175 K.
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Griffin, Matt. "Beyond FIRST and Planck". Symposium - International Astronomical Union 201 (2005): 395–99. http://dx.doi.org/10.1017/s0074180900216495.
Testo completoAbstract (sommario):
Prospects for future satellite missions, operating in the FIR-mm wavelength region, to study the polarisation of the cosmic background radiation (CBR) and to carry out imaging and spectroscopy of high-redshift galaxies, are discussed. Full characterisation of the CBR polarisation offers the possibility of determining the energy scale of inflation and constraining the form of the inflaton potential. Current technology in FIR imaging and spectroscopy falls well short of matching capabilities in the optical/UV and the mm regions. Filling this gap is important to allow detailed examination of the physics and evolution of high-redshift galaxies, and will be possible with future FIR observatories which are now being studied.
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Saturni, F. G., M. Bischetti, E. Piconcelli, A. Bongiorno, C. Cicone, C. Feruglio, F. Fiore et al. "Restframe UV-to-optical spectroscopy of APM 08279+5255". Astronomy & Astrophysics 617 (settembre 2018): A118. http://dx.doi.org/10.1051/0004-6361/201832794.
Testo completoAbstract (sommario):
We present the analysis of the restframe optical-to-UV spectrum of APM 08279+5255, a well-known lensed broad absorption line (BAL) quasar at z = 3.911. The spectroscopic data were taken with the optical DOLoRes and near-IR NICS instruments at TNG, and include the previously unexplored range between C III] λ1910 and [O III] λλ4959,5007. We have investigated the possible presence of multiple BALs by computing “balnicity” and absorption indexes (i.e., BI, BI0, and AI) for the transitions Si IV λ1400, C IV λ1549, Al III λ1860, and Mg II λ2800. No clear evidence for the presence of absorption features is found in addition to the already known, prominent BAL associated to C IV, which supports a high-ionization BAL classification for APM 08279+5255. We also studied the properties of the [O III], Hβ, and Mg II emission lines. We find that [O III] is intrinsically weak (F[OIII]∕FHβ ≲ 0.04), as it is typically found in luminous quasars with a strongly blueshifted C IV emission line (~2500 km s−1 for APM 08279+5255). We computed the single-epoch black hole mass based on Mg II and Hβ broad emission lines, finding MBH = (2 ÷ 3) × 1010μ−1 M⊙, with the magnification factor μ that can vary between 4 and 100 according to CO and restframe UV-to-mid-IR imaging respectively. Using a Mg II equivalent width (EW)-to-Eddington ratio relation, the EWMgII ~ 27 Å measured for APM 08279+5255 translates into an Eddington ratio of ~0.4, which is more consistent with μ = 4. This magnification factor also provides a value of MBH that is consistent with recent reverberation-mapping measurements derived from C IV and Si IV.
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Liu, Ruizeng, Bin Pei, Zhicheng Liu, Yunwei Wang, Jialei Li e Dianwen Liu. "Improved Understanding of the Sulfidization Mechanism in Amine Flotation of Smithsonite: An XPS, AFM and UV–Vis DRS Study". Minerals 10, n. 4 (20 aprile 2020): 370. http://dx.doi.org/10.3390/min10040370.
Testo completoAbstract (sommario):
Sulfidization is required in the amine flotation of smithsonite; however, the sulfidization mechanism of smithsonite is still not fully understood. In this work, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS) were used to characterize sulfidized and unsulfidized smithsonite. The XPS and UV–vis DRS analyses showed that smithsonite sulfidization is a transformation of ZnCO3 to ZnS on the smithsonite surfaces. However, this transformation is localized, resulting in the coexistence of ZnCO3 and ZnS or in the formation of ZnS island structures on the sulfidized smithsonite surfaces. AFM height imaging showed that sulfidization can substantially change the surface morphology of smithsonite; in addition, AFM phase imaging demonstrated that sulfidization occurs locally on the smithsonite surfaces. Based on our findings, it can be concluded that smithsonite sulfidization is clearly a heterogeneous solid–liquid reaction in which the solid product attaches at the surfaces of unreacted smithsonite. Smithsonite sulfidization involves heterogeneous nucleation and growth of ZnS nuclei. Moreover, the ZnS might nucleate and grow preferentially in the regions with high reactivity, which might account for the formation of ZnS island structures. In addition, sphalerite-structured ZnS is more likely to be the sulfidization product of smithsonite under flotation-relevantconditions, as also demonstrated by the results of our UV–vis DRS analyses. The results of this study can provide deeper insights into the sulfidization mechanism of smithsonite.