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Articoli di riviste sul tema "Photon spectrometry"

Autore: Grafiati

Pubblicato: 14 dicembre 2024

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1

Behrens, Rolf, Hayo Zutz e Julian Busse. "Spectrometry of pulsed photon radiation". Journal of Radiological Protection 42, n. 1 (17 gennaio 2022): 011507. http://dx.doi.org/10.1088/1361-6498/ac3dd0.

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Abstract The energy distribution (spectrum) of pulsed photon radiation can hardly be measured using active devices, therefore, a thermoluminescence detector (TLD)-based few-channel spectrometer is used in combination with a Bayesian data analysis to help resolve this problem. The spectrometer consists of 30 TLD layers interspaced by absorbers made of plastics and metals with increasing atomic numbers and thickness. Thus, the main idea behind the device is the deeper the radiation penetrates—the higher the radiation’s energy when the radiation impinges perpendicular to the front of the spectrometer. From the doses measured in the TLD layers and from further prior available information, the photon spectrum is deduced using a Bayesian data analysis leading to absolute spectra and doses including their uncertainties and coverage intervals. This spectrometer was successfully used in two different scenarios, i.e. for the spectrometry of the radiation field two different industrial type open beam pulsed x-ray generators and secondly in three different radiation fields of a medical accelerator.

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2

Lockyer, Nicholas P., e John C. Vickerman. "Single Photon Ionisation Mass Spectrometry Using Laser-Generated Vacuum Ultraviolet Photons". Laser Chemistry 17, n. 3 (1 gennaio 1997): 139–59. http://dx.doi.org/10.1155/1997/53174.

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This paper provides an overview of the method of single photon ionisation mass spectrometry. A review of the theory of frequency upconversion using third-order 4- wave sum mixing in isotropic media and experimental results of third harmonic generation (THG) using a frequency tripled 355 nm Nd:YAG pump source are presented. Vacuum Ultra-violet (VUV) photons of wavelength 118 nm are detected in an acetone ionisation chamber. The emphasis of this paper is on the practical aspects of generating and detecting the VUV photons and using them for single photon ionisation (SPI) in the ion source of a mass spectrometer. Optimum gas pressures for THG in Xe and Xe/Ar mixtures are established. For a pump beam of well defined mode structure the optimum gas pressures are in excellent agreement with theory. The major loss mechanism is attributed to re-absorption of VUV by the tripling gas. SPI mass spectra of hexane and the biomolecule valyl-valine are presented illustrating the power of the technique.

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3

Fairbank, W. M. "Photon burst mass spectrometry". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 29, n. 1-2 (novembre 1987): 407–14. http://dx.doi.org/10.1016/0168-583x(87)90274-6.

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4

Besnard-Vauterin, C., V. Blideanu e B. Rapp. "Development of a new method for the detection of illicit materials based on the Active Photon Interrogation Method and photo-neutron spectrometry". EPJ Web of Conferences 288 (2023): 06004. http://dx.doi.org/10.1051/epjconf/202328806004.

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The detection of illicit materials is a critical task in the field of homeland security, as international trade has contributed to the increase of smuggling activities. Nonintrusive on-site inspections are crucial in this context, but the current active interrogation methods have limitations. Neutron-induced reactions have been used, but the measurement of gamma spectra is complex due to background noise. Active photon interrogation methods have also been overlooked but they are currently limited to actinides detection using photo-fission reactions. This work presents a novel method for the detection of illicit materials based on active photon interrogation and photo-neutron spectrometry. This approach extends the application of active photon interrogation by including the detection of conventional explosives, narcotics, and chemical weapons based on the use photo-nuclear reactions to determine the content of light elements such as nitrogen, oxygen, and carbon. Monte-Carlo codes are the main tool used to simulate this process for the application need. However, because of the lack in the present literature of measured neutron spectra, the experimental validation of the simulations is not straight forward. At present, benchmarking the Monte-Carlo codes seems to be the sole option for testing their ability to accurately simulate photo-neutron production and spectra for the nuclear reactions of interest. Simultaneously, we designed a test bench based on a linear accelerator to generate photons, induce photonuclear reactions, and acquire photo-neutron spectra. This study on the fundamental aspects of photo-neutron production lays the groundwork for a promising new detection method for illicit materials.

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Klein, H. "Photon spectrometry in mixed fields". Radiation Protection Dosimetry 107, n. 1-3 (1 novembre 2003): 125–31. http://dx.doi.org/10.1093/oxfordjournals.rpd.a006381.

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6

Omori, Yasutaka, Atsuyuki Sorimachi, Masahiro Hosoda, Sarata Kumar Sahoo, Norbert Kavasi, Osamu Kurihara, Shinji Tokonami e Tetsuo Ishikawa. "Improvement of spectral analysis using a NaI(Tl) scintillation spectrometer to evaluate ambient gamma dose rates from primordial radionuclides". Radiation Protection Dosimetry 199, n. 18 (novembre 2023): 2233–37. http://dx.doi.org/10.1093/rpd/ncad258.

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Abstract In-situ measurements by gamma-ray spectrometry using a NaI(Tl) scintillation spectrometer are performed to discriminate primordial and artificial radionuclides contributing to ambient gamma dose rates in the living environment to quantify prolonged influence of nuclear accidents. However, low energy resolution of the spectrometer causes poor discrimination in the measurements at high-dose-rate points, which leads to overestimation of ambient gamma dose rate from the primordial radionuclides. The present study clarified that photon fluxes originating from 40K and 214Bi were affected by the presence of 134Cs, whereas those from 208Tl were independent of it. In addition, the absorbed dose rates in air were strongly correlated with the 208Tl photon fluxes. These findings indicate that 208Tl photon fluxes can be used to evaluate absorbed dose rates in air from the primordial radionuclides. When estimated from the 208Tl photon fluxes only, the absorbed dose rates in air in Namie Town and Okuma Town, locations affected by the Fukushima Dai-ichi Nuclear Power Plant accident, were 19–71 and 20–47 nGy h−1, respectively.

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Šolc, J., P. Dryák, J. Rusňák, V. Sochor e Z. Vykydal. "Practical X-ray beam spectrometry with cadmium telluride detector in 10–300 kVp range at Czech Metrology Institute. Part II. Unfolding". Journal of Instrumentation 17, n. 10 (1 ottobre 2022): P10003. http://dx.doi.org/10.1088/1748-0221/17/10/p10003.

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Abstract The paper summarizes computational methods and software tools used at Czech Metrology Institute for unfolding of X-ray photon fluence spectra from detector spectra measured with a cadmium telluride (CdTe) spectrometer directly in the X-ray beam. Fluence spectra were determined using multi-channel unfolding software GRAVEL. Response functions were calculated by Monte Carlo (MC) method using the general-purpose code MCNP® in version 6.2 with EPRDATA14 photon cross-section tables. The detailed MC model of the CdTe spectrometer was developed and it was validated by comparison with full-energy peak detection efficiencies measured with selected radionuclide sources. The adopted methods and tools enable to fulfil requirements of the ISO 4037 standard dealing with the necessity of direct measurement of X-ray beam photon fluence spectra whose parameters do not comply with the ones listed in the standard. The instrumentation part for the X-ray beam spectrometry at CMI is described in a separate paper [1].

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8

Lamprou, Theocharis, Rodrigo Lopez-Martens, Stefan Haessler, Ioannis Liontos, Subhendu Kahaly, Javier Rivera-Dean, Philipp Stammer et al. "Quantum-Optical Spectrometry in Relativistic Laser–Plasma Interactions Using the High-Harmonic Generation Process: A Proposal". Photonics 8, n. 6 (29 maggio 2021): 192. http://dx.doi.org/10.3390/photonics8060192.

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Quantum-optical spectrometry is a recently developed shot-to-shot photon correlation-based method, namely using a quantum spectrometer (QS), that has been used to reveal the quantum optical nature of intense laser–matter interactions and connect the research domains of quantum optics (QO) and strong laser-field physics (SLFP). The method provides the probability of absorbing photons from a driving laser field towards the generation of a strong laser–field interaction product, such as high-order harmonics. In this case, the harmonic spectrum is reflected in the photon number distribution of the infrared (IR) driving field after its interaction with the high harmonic generation medium. The method was implemented in non-relativistic interactions using high harmonics produced by the interaction of strong laser pulses with atoms and semiconductors. Very recently, it was used for the generation of non-classical light states in intense laser–atom interaction, building the basis for studies of quantum electrodynamics in strong laser-field physics and the development of a new class of non-classical light sources for applications in quantum technology. Here, after a brief introduction of the QS method, we will discuss how the QS can be applied in relativistic laser–plasma interactions and become the driving factor for initiating investigations on relativistic quantum electrodynamics.

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Kudo, K., N. Takeda, S. Koshikawa, H. Toyokawa, H. Ohgaki e M. Matzke. "Photon spectrometry in thermal neutron standard field". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 476, n. 1-2 (gennaio 2002): 213–17. http://dx.doi.org/10.1016/s0168-9002(01)01434-6.

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Aleksandrov, D., J. Alme, V. Basmanov, B. Batyunya, D. Blau, M. Bogolyubsky, V. Budilov et al. "Solving a Deconvolution Problem in Photon Spectrometry". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 620, n. 2-3 (agosto 2010): 526–33. http://dx.doi.org/10.1016/j.nima.2010.03.148.

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11

Madunil, Siddihalu Lakshitha, Totaro Imasaka e Tomoko Imasaka. "Resonant and non-resonant femtosecond ionization mass spectrometry of organochlorine pesticides". Analyst 145, n. 3 (2020): 777–83. http://dx.doi.org/10.1039/c9an01861a.

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12

Shi, Y. J., e R. H. Lipson. "An overview of organic molecule soft ionization using vacuum ultraviolet laser radiation". Canadian Journal of Chemistry 83, n. 11 (1 novembre 2005): 1891–902. http://dx.doi.org/10.1139/v05-193.

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The utility of coherent vacuum ultraviolet (VUV) single-photon ionization (SPI) combined with time-of-flight mass spectrometry (TOF-MS) for organic molecule detection by parent mass is explored in this short review. Nonresonant tripling in phase-matched XeAr gas mixtures was used to generate photons at a fixed energy of 10.5 eV. Representative organic molecules with different functional groups were examined, including aliphatic and aromatic alkanes, alkenes, alkynes, alkanols, ethers, amines, aldehydes, ketones, carboxylic acids, and esters. In almost every case, the intensity of the resultant parent molecular ion peak detected by TOF-MS was found to be superior to that obtained using 70 eV electron impact (EI), and comparable to that obtained with 12 eV EI. In those instances when fragmentation reactions did occur, the resultant ions were similar to those found using EI but with significantly reduced mass spectral intensities. It was still possible to establish one dominant fragmentation pathway that could be used for molecular identification even if the parent molecular ion was not the strongest feature in the spectrum, for example, in the case of alcohols, alcohol clusters, and alcoholether adducts. Several of the fragment ions were metastably broadened. Not surprisingly, their known appearance energies or estimated reaction enthalpies were very similar to the fixed photon energy used. The success of using VUV for organic molecule soft ionization is attributed to the low photon energy that removes predominantly a π- or non-bonding electron from the functionalized species. As most organic compounds have ionization potentials in the 10.5 eV region, this approach is expected to be near universal.Key words: vacuum ultraviolet laser, single photon ionization, organic molecule detection, soft-ionization, mass spectrometry.

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13

OGAWA, TEIICHIRO. "RECENT PROGRESS IN LASER MULTI-PHOTON IONIZATION SPECTROMETRY". Analytical Sciences 7, Supple (1991): 1475–78. http://dx.doi.org/10.2116/analsci.7.supple_1475.

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14

Neumann, S., R. Böttger, S. Guldbakke, M. Matzke e W. Sosaat. "Neutron and photon spectrometry in monoenergetic neutron fields". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 476, n. 1-2 (gennaio 2002): 353–57. http://dx.doi.org/10.1016/s0168-9002(01)01469-3.

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15

Neusser, H. J. "Multi-photon mass spectrometry and unimolecular ion decay". International Journal of Mass Spectrometry and Ion Processes 79, n. 2 (ottobre 1987): 141–81. http://dx.doi.org/10.1016/0168-1176(87)83014-8.

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16

Goncalves, J. A. C., F. Camargo, M. M. R. Fraga, J. K. C. Pinto e C. C. Bueno. "Rad-Hard Silicon Diode Response for Photon Spectrometry". IEEE Transactions on Nuclear Science 54, n. 1 (febbraio 2007): 276–79. http://dx.doi.org/10.1109/tns.2006.887856.

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17

Švec, Anton. "Photon energy conversion efficiency in gamma-ray spectrometry". Applied Radiation and Isotopes 107 (gennaio 2016): 103–8. http://dx.doi.org/10.1016/j.apradiso.2015.09.015.

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18

Šolc, J., P. Dryák, J. Rusňák, V. Sochor e Z. Vykydal. "Practical X-ray beam spectrometry with cadmium telluride detector in 10–300 kVp range at Czech Metrology Institute. Part I. Instrumentation". Journal of Instrumentation 17, n. 10 (1 ottobre 2022): P10002. http://dx.doi.org/10.1088/1748-0221/17/10/p10002.

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Abstract The paper describes instrumentation used at Czech Metrology Institute for measurement of photon fluence spectra directly in X-ray beams. Detector with a cadmium telluride (CdTe) sensor was characterized by means of energy resolution and precise energy calibration. The hole trapping effect in CdTe causing full-energy peak deformations in measured spectra was adopted consisting of analytical models of incomplete charge collection and carrier trapping based on Hecht equation. The detector collimator provided by the manufacturer was modified with additional tungsten shielding that effectively absorbs the majority of photons scattered in the collimator body resulting in significant improvement of the consistency of measured and Monte Carlo simulated detector response. The purpose-made alignment platform increased the accuracy of orientation of the collimator axis improving the measurement in high photon fluence rate beams using collimation disks with very small apertures (down to 100 μm in diameter). The adopted instrumentation and methods for X-ray beam spectrometry enabled to fulfil the requirements of the new ISO 4037:2019-ed.2.0 standard for reference metrology laboratories. Software-focused part dealing with Monte Carlo simulations and procedures for photon fluence spectra unfolding is summarized in [1].

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Hale, Oliver J., e Helen J. Cooper. "In situ mass spectrometry analysis of intact proteins and protein complexes from biological substrates". Biochemical Society Transactions 48, n. 1 (3 febbraio 2020): 317–26. http://dx.doi.org/10.1042/bst20190793.

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Advances in sample preparation, ion sources and mass spectrometer technology have enabled the detection and characterisation of intact proteins. The challenges associated include an appropriately soft ionisation event, efficient transmission and detection of the often delicate macromolecules. Ambient ion sources, in particular, offer a wealth of strategies for analysis of proteins from solution environments, and directly from biological substrates. The last two decades have seen rapid development in this area. Innovations include liquid extraction surface analysis, desorption electrospray ionisation and nanospray desorption electrospray ionisation. Similarly, developments in native mass spectrometry allow protein–protein and protein–ligand complexes to be ionised and analysed. Identification and characterisation of these large ions involves a suite of hyphenated mass spectrometry techniques, often including the coupling of ion mobility spectrometry and fragmentation techniques. The latter include collision, electron and photon-induced methods, each with their own characteristics and benefits for intact protein identification. In this review, recent developments for in situ protein analysis are explored, with a focus on ion sources and tandem mass spectrometry techniques used for identification.

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20

Yeni, Oznur, Baptiste Schindler, Baptiste Moge e Isabelle Compagnon. "Rapid IRMPD (InfraRed multiple photon dissociation) analysis for glycomics". Analyst 147, n. 2 (2022): 312–17. http://dx.doi.org/10.1039/d1an01870a.

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OGAWA, Teiichiro. "Highly sensitive analysis by laser multi-photon ionization spectrometry." Bunseki kagaku 42, n. 4 (1993): 201–7. http://dx.doi.org/10.2116/bunsekikagaku.42.4_201.

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22

Steyn, G. F., S. G. Dolley, F. Szelecsényi, Z. Kovács, N. P. van der Meulen e C. Vermeulen. "In-flight annihilation correction for 511 keV photon spectrometry". EPJ Web of Conferences 146 (2017): 08010. http://dx.doi.org/10.1051/epjconf/201714608010.

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23

Comstock, Matthew G., Jeffrey R. Kerr e Jeffrey A. Gray. "Two-Photon Ionization Spectrometry of Alkali Atoms in Flames". Journal of Chemical Education 79, n. 4 (aprile 2002): 500. http://dx.doi.org/10.1021/ed079p500.

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Dubois, F., R. Knochenmuss e R. Zenobi. "An ion-to-photon conversion detector for mass spectrometry". International Journal of Mass Spectrometry and Ion Processes 169-170 (dicembre 1997): 89–98. http://dx.doi.org/10.1016/s0168-1176(97)00210-3.

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Nogar, N. S., S. W. Downey e C. M. Miller. "Multiple photon processes in tantalum resonance ionization mass spectrometry". Analytical Chemistry 57, n. 6 (maggio 1985): 1144–47. http://dx.doi.org/10.1021/ac00283a041.

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26

Fischer, M., S. Wohlfahrt, J. Varga, M. Saraji-Bozorgzad, G. Matuschek, T. Denner e R. Zimmermann. "Evolved gas analysis by single photon ionization-mass spectrometry". Journal of Thermal Analysis and Calorimetry 116, n. 3 (13 maggio 2014): 1461–69. http://dx.doi.org/10.1007/s10973-014-3830-3.

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Fernández, J. E. "Polarization effects and photon transport in x-ray spectrometry". X-Ray Spectrometry 24, n. 6 (novembre 1995): 283–92. http://dx.doi.org/10.1002/xrs.1300240603.

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Yu, Zhujun, Chao Liu, Hongzhi Niu, Manman Wu, Wei Gao, Zhen Zhou, Zhengxu Huang e Xue Li. "Real time analysis of trace volatile organic compounds in ambient air: a comparison between membrane inlet single photon ionization mass spectrometry and proton transfer reaction mass spectrometry". Analytical Methods 12, n. 35 (2020): 4343–50. http://dx.doi.org/10.1039/d0ay01102a.

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Membrane single photon ionization mass spectrometry enables real-time monitoring of volatile organic compounds at trace levels, providing important complementary information on aromatics and alkanes in the air.

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Schläppi, Bernhard, Jessica H. Litman, Jorge J. Ferreiro, David Stapfer e Ruth Signorell. "A pulsed uniform Laval expansion coupled with single photon ionization and mass spectrometric detection for the study of large molecular aggregates". Physical Chemistry Chemical Physics 17, n. 39 (2015): 25761–71. http://dx.doi.org/10.1039/c5cp00061k.

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Gehm, Christian, Kevin Schnepel, Hendryk Czech, Toni Miersch, Sven Ehlert e Ralf Zimmermann. "Hyper-fast gas chromatography and single-photon ionisation time-of-flight mass spectrometry with integrated electrical modulator-based sampling for headspace and online VOC analyses". Analyst 146, n. 10 (2021): 3137–49. http://dx.doi.org/10.1039/d1an00114k.

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We developed a novel fast gas chromatography (fastGC) instrument with integrated sampling of volatile organic compounds (VOCs) and detection by single-photon ionisation (SPI) time-of-flight mass spectrometry (TOFMS).

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Bulak, M., D. M. Paardekooper, G. Fedoseev e H. Linnartz. "Novel approach to distinguish between vacuum UV-induced ice photodesorption and photoconversion". Astronomy & Astrophysics 636 (aprile 2020): A32. http://dx.doi.org/10.1051/0004-6361/201937298.

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Context. In cold regions of the interstellar medium with intense ultraviolet radiation fields, photodesorption has been suggested as a nonthermal desorption mechanism promoting the transition of molecules from the solid state to the gas phase. Laboratory experiments measuring photodesorption rates are crucial in attempting to explain high molecular gas phase abundances of species that are expected to form in the solid state, such as methane, methanol, and acetonitrile, and to aid astrochemical modeling. Due to the convoluted competition between photodesorption and photoconversion, it is far from trivial to derive accurate photodesorption rates. Aims. The aim of this study is to apply a new methodology to discriminate between the two processes. The method has been validated using the well-studied case of CO and extended to CH4, CH3OH, and CH3CN. Methods. Vacuum ultraviolet (VUV; photon energy of 7–10.2 eV) irradiated ices at 20 K are studied, first as a pure CH4, CH3OH, or CH3CN ice and subsequently with an Ar coating on top. The latter is transparent to the VUV photons (wavelength below 200 nm), but it quenches the photodesorption process. Comparing the laser desorption post ionization time-of-flight mass spectrometry of the ices with and without the Ar coating provides information on the different interactions of the VUV photons with the ice. Results. The newly developed experimental technique allowed for a derivation of photodesorption rates for ices at 20 K of: CO (3.1 ± 0.3)×10−3 mol. photon−1, CH4 (3.1 ± 0.5)×10−2 mol. photon−1, and upper limits for CH3OH (< 6 × 10−5 mol. photon−1) and CH3CN (< 7.4 × 10−4 mol. photon−1); in the latter case, no literature values have been reported yet. The newly introduced approach provides more insight into the photodesorption process, in particular, for commonly observed complex organic molecules (COMs). Photoconversion cross sections are presented in the 7–10.2 eV range. The possible role of photodesorption and photoconversion in the formation of interstellar COMs is discussed.

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Liu, Ping, Yongjun Hu, Guichi Zhu, Qing Yang e Yanmin Tao. "Direct and fast detection of chlorothalonil in soil samples using laser desorption VUV single photon post-ionization mass spectrometry". Analytical Methods 7, n. 16 (2015): 6890–95. http://dx.doi.org/10.1039/c5ay01097g.

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Pan, Yu-Lu, Zhi-Bin Cai, Li Bai, Sheng-Li Li e Yu-Peng Tian. "Preparation and Photophysical Properties of All-trans Acceptor–π-Donor (Acceptor) Compounds Possessing Obvious Solvatochromic Effects". Australian Journal of Chemistry 70, n. 9 (2017): 1048. http://dx.doi.org/10.1071/ch17021.

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A series of all-trans acceptor–π-donor (acceptor) compounds (BAQ, SFQ, BLQ, and XJQ) were conveniently synthesised and characterised by infrared, nuclear magnetic resonance, mass spectrometry, and elemental analysis. Their photophysical properties, including linear absorption, one-photon excited fluorescence, two-photon absorption, and two-photon excited fluorescence, were systematically investigated. All the compounds show obvious solvatochromic effects, such as significant bathochromic shifts of the emission spectra and larger Stokes shifts in more polar solvents. Under excitation from a femtosecond Ti : sapphire laser with a pulse width of 140 fs, they all exhibit strong two-photon excited fluorescence, and the two-photon absorption cross-sections in THF are 851 (BAQ), 216 (SFQ), 561 (BLQ), and 447 (XJQ) GM respectively. A combination of density functional theory (DFT) and time-dependent density functional theory (TDDFT) approaches was used to investigate the relationships between the structures and the photophysical properties of these compounds. The results show that they may have a potential application as polarity-sensitive two-photon fluorescent probes.

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Sakanoue, M., M. Yamamoto e K. Komura. "Determination of environmental actinide nuclides and210Pb(210Po) by low-energy photon spectrometry with alpha-spectrometry". Journal of Radioanalytical and Nuclear Chemistry Articles 115, n. 1 (ottobre 1987): 71–82. http://dx.doi.org/10.1007/bf02041977.

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Scuderi, D., A. Paladini, M. Satta, D. Catone, F. Rondino, A. Filippi, S. Piccirillo, M. Speranza e A. Giardini Guidoni. "Solvent free interactions in contact pairs of molecules of biological interest: Laser spectroscopic and electrospray mass spectrometric studies". International Journal of Photoenergy 6, n. 1 (2004): 17–21. http://dx.doi.org/10.1155/s1110662x04000030.

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A laser spectroscopic and mass spectrometric study of ionic and molecular clusters of biological interest is reported. The molecules of interest and their aggregates were generated in a supersonic beam and analyzed by mass resolved resonant two photon absorption and ionization (R2PI) and by collision induced mass spectrometry (CID-MS). The absence of the solvent allows to study these systems in the isolated state free of undesired solvent effects which may level off the differences in their properties. The gas phase results have been compared to theoretical estimates of the structure and stability of the systems under investigation.

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Gnaser, Hubert, Martin Martschini, David Leimbach, Julia Karls, Dag Hanstorp, Suvasthika Indrajith, Mingchao Ji et al. "Spontaneous and photo-induced decay processes of WF5− and HfF5− molecular anions in a cryogenic storage ring". Journal of Chemical Physics 157, n. 4 (28 luglio 2022): 044304. http://dx.doi.org/10.1063/5.0097896.

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Spontaneous and photo-induced decay processes of HfF5− and WF5− molecular anions were investigated in the Double ElectroStatic Ion Ring ExpEriment (DESIREE). The observation of these reactions over long time scales (several tens of ms) was possible due to the cryogenic temperatures (13 K) and the extremely low residual gas pressure (∼10−14 mbar) of DESIREE. For photo-induced reactions, laser wavelengths in the range 240 to 450 nm were employed. Both anion species were found to undergo spontaneous decay via electron detachment or fragmentation. After some ms, radiative cooling processes were observed to lower the probability for further decay through these processes. Photo-induced reactions indicate the existence of an energy threshold for WF5− anions at about 3.5 eV, above which the neutralization yield increases strongly. By contrast, HfF5− ions exhibit essentially no enhanced production of neutrals upon photon interaction, even for the highest photon energy used in this experiment (∼5.2 eV). This suppression will be highly beneficial for the efficient detection, in accelerator mass spectrometry, of the extremely rare isotope 182Hf using the 182HfF5− anion while effectively reducing the interfering stable isobar 182W in the analyte ion 182WF5−. The radionuclide 182Hf is of great relevance in astrophysical environments as it constitutes a potential candidate to study the events of nucleosynthesis that may have taken place in the vicinity of the solar system several million years ago.

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Ntalla, E., A. Markopoulos, K. Karfopoulos, C. Potiriadis, A. Clouvas e A. Savidou. "Development of a semi-empirical calibration method by using a LaBr3(Ce) scintillation detector for NORM samples analyses". HNPS Advances in Nuclear Physics 27 (19 aprile 2021): 199. http://dx.doi.org/10.12681/hnps.3213.

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Abstract (sommario):

In this study, a semi-empirical calibration method for NORM samples measurement by using a LaBr3(Ce) scintillator was developed based on a combination of experimental gamma spectrometry measurements and MCNP-X simulations. The aim of this work is to provide us with full energy peak efficiency calibration curves in a wide photon energy range which is of particular importance when selected photon energies of 234Th, 214Pb, 214Bi, 228Ac, 208Tl and 226Ra are to be measured with accuracy.

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38

Suryanarayana, M. V., M. Sankari e S. Gangadharan. "Determination of 6Li/7Li isotope ratio using two photon resonance three photon resonance ionisation mass spectrometry". International Journal of Mass Spectrometry and Ion Processes 173, n. 3 (febbraio 1998): 177–89. http://dx.doi.org/10.1016/s0168-1176(97)00282-6.

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39

HUESTIS, DAVID L., CHRISTOPHER MULLEN, MICHAEL J. COGGIOLA e HARALD OSER. "LASER-IONIZATION MASS SPECTROMETRY OF EXPLOSIVES AND CHEMICAL WARFARE SIMULANTS". International Journal of High Speed Electronics and Systems 18, n. 01 (marzo 2008): 159–65. http://dx.doi.org/10.1142/s0129156408005230.

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Abstract (sommario):

The objective of the present study was to better understand the photophysics of explosives and chemical warfare simulants in order to develop better performing analytical tools. Photoionization mass spectra were taken using three optical schemes. The first was resonance-enhanced multiphoton ionization (REMPI) using few-ns duration 248 or 266 nm laser pulses. The second scheme was non-resonant multiphoton ionization (MPI) using 100 fs duration laser pulses at wavelengths between 325 and 795. The third approach was single photon ionization (SPI) using few-ns duration 118 nm laser pulses. For all the molecules investigated, mass spectra resulting exposure to ns-duration 248 or 266 nm laser pulses consisted of only low molecular weight fragments. Using fs-duration laser pulses produced more complicated, potentially analyzable, fragmentation patterns, usually with some parent peak. Single photon ionization gave the best results, with mass spectra consisting of almost only parent peak, except for the case of TATP.

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40

Apel, E. C., J. E. Anderson, R. C. Estler, N. S. Nogar e C. M. Miller. "Use of two-photon excitation in resonance ionization mass spectrometry". Applied Optics 26, n. 6 (15 marzo 1987): 1045. http://dx.doi.org/10.1364/ao.26.001045.

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41

Juranić, P. N., M. Martins, J. Viefhaus, S. Bonfigt, L. Jahn, M. Ilchen, S. Klumpp e K. Tiedtke. "Using I-TOF spectrometry to measure photon energies at FELs". Journal of Instrumentation 4, n. 09 (25 settembre 2009): P09011. http://dx.doi.org/10.1088/1748-0221/4/09/p09011.

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42

Nash, David G., X. Frank Liu, Erin R. Mysak e Tomas Baer. "Aerosol particle mass spectrometry with low photon energy laser ionization". International Journal of Mass Spectrometry 241, n. 2-3 (marzo 2005): 89–97. http://dx.doi.org/10.1016/j.ijms.2004.12.016.

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43

Zhu, Suyun, Mattia Scardamaglia, Jan Kundsen, Rami Sankari, Hamed Tarawneh, Robert Temperton, Louisa Pickworth et al. "HIPPIE: a new platform for ambient-pressure X-ray photoelectron spectroscopy at the MAX IV Laboratory". Journal of Synchrotron Radiation 28, n. 2 (12 febbraio 2021): 624–36. http://dx.doi.org/10.1107/s160057752100103x.

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Abstract (sommario):

HIPPIE is a soft X-ray beamline on the 3 GeV electron storage ring of the MAX IV Laboratory, equipped with a novel ambient-pressure X-ray photoelectron spectroscopy (APXPS) instrument. The endstation is dedicated to performing in situ and operando X-ray photoelectron spectroscopy experiments in the presence of a controlled gaseous atmosphere at pressures up to 30 mbar [1 mbar = 100 Pa] as well as under ultra-high-vacuum conditions. The photon energy range is 250 to 2200 eV in planar polarization and with photon fluxes >1012 photons s−1 (500 mA ring current) at a resolving power of greater than 10000 and up to a maximum of 32000. The endstation currently provides two sample environments: a catalysis cell and an electrochemical/liquid cell. The former allows APXPS measurements of solid samples in the presence of a gaseous atmosphere (with a mixture of up to eight gases and a vapour of a liquid) and simultaneous analysis of the inlet/outlet gas composition by online mass spectrometry. The latter is a more versatile setup primarily designed for APXPS at the solid–liquid (dip-and-pull setup) or liquid–gas (liquid microjet) interfaces under full electrochemical control, and it can also be used as an open port for ad hoc-designed non-standard APXPS experiments with different sample environments. The catalysis cell can be further equipped with an IR reflection–absorption spectrometer, allowing for simultaneous APXPS and IR spectroscopy of the samples. The endstation is set up to easily accommodate further sample environments.

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44

Andermann, George, Francis Fujiwara, T. C. Huang, J. K. Howard e N. Staud. "Characterization of Permalloy Thin Films via Variable Sample Exit Angle Ultrasoft X-ray Fluorescence Spectrometry". Advances in X-ray Analysis 32 (1988): 261–68. http://dx.doi.org/10.1154/s0376030800020565.

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Abstract (sommario):

Recently variable sample exit-angle x-ray fluorescence spectrometry (VEA-XRF) has been shorn to be a useful analytical tool for monitoring the oxidation of the surfaces of bulk Cu, Ni as well as that of Fe. In these studies advantage was taken of the well known phenomenon that for each transition metal oxide (MO) Lβ/Lα intensity ratio value is higher than for the transition metal (M), itself. Within the limits of the photon-escape depth de, which for these photons are generally below 5000 Å, varying the sample exit-angle θ offers an opportunity for seeing whether or not the oxidation of the surfaces of bulk M belongs to one of the following two classes: (I) uniform oxidation throughout the entire observable sample-depth, (II) preferential oxidation of the top surface layer, i.e. depth dependent oxidation.

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45

Quevauvillers, Diane, Laurent Ottaviani, Michael Petit e Christelle Reynard-Carette. "Characterization and use of Stilbene scintillator for neutron metrology and spectrometry from 100 keV to 22 MeV". EPJ Web of Conferences 288 (2023): 10006. http://dx.doi.org/10.1051/epjconf/202328810006.

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Abstract (sommario):

Stilbene scintillators have now the capability to extend the neutron energy measurement from 100 keV to 1 MeV. To be used as spectrometers, scintillators have to be characterized in entire energy range covered. For the photon characterization, usual calibration source determined the calibration and the resolution function. To do the photon matrix, MCNP PTRAC simulations were done between 59 keV up to 7 MeV. Using MCNP PTRAC allows the calculation of the photon response matrix from the tracking detail of the electron energy deposition in the crystal, including the effect of the Aluminum protection around. Resolution and sensibility obtained from gamma sources are applied later to the calculated photon matrix. For neutron characterization, Time-Of-Flight measurements on white neutron spectra were realized. However, the fluence reference on these spectra begins at 1 MeV. So, the shape of the response function was measured using stilbene scintillators on 100 keV1 MeV decade. After, the monoenergetic neutron reference of AMANDE facility was used to give neutron fluence normalization below 1 MeV. This method could characterize these scintillators for neutron energy from 100 keV up to 22 MeV.

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46

Frankevich, Vladimir, Xianwen Guan, Maxim Dashtiev e Renato Zenobi. "Laser-Induced Fluoresence of Trapped Gas-Phase Molecular Ions Generated by Internal-Source Matrix-Assisted Laser Desorption/Ionization in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer". European Journal of Mass Spectrometry 11, n. 5 (ottobre 2005): 475–82. http://dx.doi.org/10.1255/ejms.720.

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Abstract (sommario):

The combination of laser-induced fluorescence with mass spectrometry opens up new possibilities both for detection purposes and for structural studies of trapped biomolecular ions in the gas phase. However, this approach is experimentally very challenging and only a handful of studies have been reported so far. In this contribution, a novel scheme for laser-induced fluorescence measurements of ions trapped inside a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer will be introduced. It is based on an open FT-ICR cell design, continuous wave axial excitation of the fluorescence, orthogonal photon collection by fiber optics and single photon counting detection. Rhodamine 6G ions generated by an internal matrix-assisted laser desorption/ionization source were used to develop and test the set-up. Due to photobleaching processes, the excitation laser power and the observation time window have to be carefully optimized. An ion tomography method was used to align the excitation laser. Potential applications for studying the gas-phase structure of fluorescent biomolecular ions and for investigating fluorescence resonance energy transfer of donor-acceptor pairs will be presented.

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47

Chen, Zhe Jay, e Ravinder Nath. "Photon spectrometry for the determination of the dose-rate constant of low-energy photon-emitting brachytherapy sources". Medical Physics 34, n. 4 (21 marzo 2007): 1412–30. http://dx.doi.org/10.1118/1.2713217.

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48

Sari, Adrien, Sara Garti, Frédéric Lainé, Frédérick Carrel, Jonathan Dumazert, Hamid Makil, Nicolas Dufour et al. "The Potential of Photon Activation and Neutron Activation Techniques for Fast Soil Characterization". EPJ Web of Conferences 225 (2020): 09001. http://dx.doi.org/10.1051/epjconf/202022509001.

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Abstract (sommario):

In the frame of a partnership between CEA and VINCI, various measurement techniques are applied to soil analysis and tested in different laboratories located at CEA Saclay (France). This paper deals with two nuclear measurement techniques assessed in this project. More specifically, this paper presents the feasibility study carried out for two non-destructive active methods: photon activation and neutron activation. First, some atomic nuclides are activated either by photons or neutrons. Secondly, gamma-rays of specific energies are emitted by activated nuclides and gamma-ray spectrometry enables to identify these activated nuclides. Calibration of the full measurement system with reference samples would enable to quantify the mass of activated nuclides. Irradiations performed for photon activation measurements were conducted using a linear electron accelerator (linac) as the latter enables to generate high-energy photons by Bremsstrahlung thanks to its conversion target. Furthermore, irradiations performed for neutron activation measurements were also conducted with a linac. Indeed, photons may be converted to neutrons by photonuclear reactions using a secondary target. In the frame of this project, experiments were carried out at the SAPHIR platform (CEA Saclay) with a Linatron-M9 VARIAN linac. The electron energy was either 6 or 9 MeV. For neutron activation measurements, a secondary target made of heavy water has been used as neutron source and a polyethylene cell enabled to thermalize neutrons and increase the number of reactions of interest. In this paper, we present the different experimental setups and the measurement protocols established for this feasibility study. We show experimental results obtained with raw material samples coming from three construction sites.

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49

Mihailescu, L. C. "X-ray spectrometry with germanium detector at a dosimetry calibration laboratory". Journal of Instrumentation 18, n. 09 (1 settembre 2023): P09037. http://dx.doi.org/10.1088/1748-0221/18/09/p09037.

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Abstract Implementation of the recommendations of the new version of the ISO 4037 standard at X-ray installations of dosimetry calibration laboratories proved to be difficult and the uncertainties on the conversion coefficients due to differences between the fluence spectra from different installations are not yet sufficiently established. The X-ray installation of SCK CEN/LNK was characterized to verify the conformity with the most recent version of the ISO 4037 standard. The Half-Value Layer (HVL) values were measured to prove that conditions for matched beam qualities are fulfilled and then photon spectrometry with a High Purity Germanium (HPGe) detector was performed to measure the fluence spectra. Using the fluence spectra, the conversion coefficients from air kerma Ka to operational quantities were calculated and compared with the recommended values from the ISO 4037 standard. Most of these coefficients agree within 2% while the ISO 4037 recommended values have an uncertainty of 4% (k = 2). Possible sources of uncertainty in the photon spectrometry were evaluated and are discussed.

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50

Smith, D. H., H. S. McKown, J. P. Young, R. W. Shaw e D. L. Donohue. "Prediction and Identification of Multiple-Photon Resonant Ionization Processes". Applied Spectroscopy 42, n. 6 (agosto 1988): 1057–61. http://dx.doi.org/10.1366/0003702884430461.

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Many single-color, multiple-photon transitions leading to ionization are observed for lanthanide and actinide elements in experiments using resonance ionization mass spectrometry (RIMS). It is desirable both to identify the energy levels involved in observed transitions and to be able to predict in advance their location. A computer code, ETRANS, has been written to perform these functions. Examples of both types of operation are given.

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