Zeitschriftenartikel: „Line spectrometers“

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Frey, M., F. Hase, T. Blumenstock, J. Groß, M. Kiel, G. Mengistu Tsidu, K. Schäfer, M. Kumar Sha und J. Orphal. „Use of portable FTIR spectrometers for detecting greenhouse gas emissions of the megacity Berlin – Part 1: Instrumental line shape characterisation and calibration of a quintuple of spectrometers“. Atmospheric Measurement Techniques Discussions 8, Nr. 3 (13.03.2015): 2735–66. http://dx.doi.org/10.5194/amtd-8-2735-2015.

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Abstract. Several low resolution spectrometers were used to investigate the CO2 and CH4 emissions of the megacity Berlin. Before and after the campaign the instruments were tested side-by-side. An excellent level of agreement and stability was found between the different spectrometers: the drifts in XCO2 and XCH4 are within 0.005 and 0.035%, respectively. The instrumental line shape characteristics of all spectrometers were found to be close to nominal. Cross-calibration factors for XCH4 and XCO2 were established for each spectrometer. An empirical airmass correction factor has been applied. As a last calibration step, using a co-located TCCON spectrometer as a reference, a common factor has been derived for the low-resolution campaign spectrometers, which ensures that the records are compatible to the WMO in-situ scale. Finally as a first result of the Berlin campaign we show the excellent agreement of ground pressure values obtained from total column measurements and in situ records.

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Frey, M., F. Hase, T. Blumenstock, J. Groß, M. Kiel, G. Mengistu Tsidu, K. Schäfer, M. K. Sha und J. Orphal. „Calibration and instrumental line shape characterization of a set of portable FTIR spectrometers for detecting greenhouse gas emissions“. Atmospheric Measurement Techniques 8, Nr. 7 (31.07.2015): 3047–57. http://dx.doi.org/10.5194/amt-8-3047-2015.

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Abstract. A comprehensive calibration procedure for mobile, low-resolution, solar-absorption FTIR spectrometers, used for greenhouse gases observations, is developed. These instruments commend themselves for campaign use and deployment at remote sites. The instrumental line shape (ILS) of each spectrometer has been thoroughly characterized by analyzing the shape of H2O signatures in open path spectra. A setup for the external source is suggested and the invariance of derived ILS parameters with regard to chosen path length is demonstrated. The instrumental line shape characteristics of all spectrometers were found to be close to nominal. Side-by-side solar observations before and after a campaign, which involved shipping of all spectrometers to a selected target site and back, are applied for verifying the temporal invariability of instrumental characteristics and for deriving intercalibration factors for XCO2 and XCH4, which take into account residual differences of instrumental characteristics. An excellent level of agreement and stability was found between the different spectrometers: the uncorrected biases in XCO2 and XCH4 are smaller than 0.01 and 0.15 %, respectively, and the drifts are smaller than 0.005 and 0.035 %. As an additional sensitive demonstration of the instrumental performance we show the excellent agreement of ground pressure values obtained from the total column measurements of O2 and barometric records. We find a calibration factor of 0.9700 for the spectroscopic measurements in comparison to the barometric records and a very small scatter between the individual spectrometers (0.02 %). As a final calibration step, using a co-located TCCON (Total Carbon Column Observation Network) spectrometer as a reference, a common scaling factor has been derived for the XCO2 and XCH4 products, which ensures that the records are traceable to the WMO in situ scale.

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Lampton, M., O. Siegmund und R. Raffanti. „Delay line anodes for microchannel‐plate spectrometers“. Review of Scientific Instruments 58, Nr. 12 (Dezember 1987): 2298–305. http://dx.doi.org/10.1063/1.1139341.

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Makarov, V. A., und T. K. Savosteenko. „Determination of phosphorus mass fraction in steels of plasma atomic emission spectrometry“. Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), Nr. 1 (26.03.2021): 86–90. http://dx.doi.org/10.21122/1683-6065-2021-1-86-90.

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A method for measuring the mass fraction of phosphorus in steels by atomic emission spectrometry with the inductively coupled plasma (AES-ICP) has been developed. Possibilities of atomic emission spectrometers of iCAP series for determination of phosphorus in steels allowing to reduce considerably duration of the analysis and to increase its profitability in comparison with chemical methods of the analysis are investigated. A method of decomposition of steel for the complete transfer of phosphorus into solution is proposed. The possibility of software spectrometers “iTeva” in the analysis by the method of relative concentrations. Calibration of the spectrometer was carried out on aqueous solutions with a known concentration of phosphorus using the method of relative concentrations. For the preparation of calibration solutions, chemically pure salt was used. The analytical line free from spectral overlays is selected. A good correlation of the calibration graph is obtained. The correctness of the determination is confirmed by the analysis of standard samples and comparison with the results of the determination in accordance with the chemical method. The developed technique is used in determining the mass fraction of phosphorus in steels. Validation of the methodology was carried out. iCAP spectrometers can be used to determine the mass fraction of phosphorus in steels.

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Tseng, Ching-Hui, Joseph F. Ford, Charles K. Mann und Thomas J. Vickers. „Wavelength Calibration of a Multichannel Spectrometer“. Applied Spectroscopy 47, Nr. 11 (November 1993): 1808–13. http://dx.doi.org/10.1366/0003702934065948.

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A readily automated procedure for wavelength calibration of multichannel spectrometers is described. Once applied, line positions can be read from the multichannel display with good accuracy and precision for any spectrometer setting. The procedure uses Ne atomic lines as wavelength standards. A novel apodization procedure is used for accurate measurement of the pixel positions of the neon lines. Raman line positions can be determined with an average error of less than 0.2 cm−1.

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Lepère, Muriel. „Line profile study with tunable diode laser spectrometers“. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 60, Nr. 14 (Dezember 2004): 3249–58. http://dx.doi.org/10.1016/j.saa.2003.12.052.

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Genest, Jérôme, und Pierre Tremblay. „Diffraction and line shape of Fourier-transform spectrometers“. Applied Optics 42, Nr. 22 (01.08.2003): 4541. http://dx.doi.org/10.1364/ao.42.004541.

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Hettrick, Michael C. „Grazing incidence echelle spectrometers using varied line-space gratings“. Applied Optics 24, Nr. 9 (01.05.1985): 1251. http://dx.doi.org/10.1364/ao.24.001251.

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Desbiens, Raphaël, Jérôme Genest und Pierre Tremblay. „Radiometry in line-shape modeling of Fourier-transform spectrometers“. Applied Optics 41, Nr. 7 (01.03.2002): 1424. http://dx.doi.org/10.1364/ao.41.001424.

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Pelipasov, O. V., R. A. Lokhtin, V. A. Labusov und N. G. Pelevina. „Analytical capabilities of a «Grand» spectrometer in analysis of solutions using inductively coupled plasma“. Industrial laboratory. Diagnostics of materials 85, Nr. 1II) (15.02.2019): 82–85. http://dx.doi.org/10.26896/1028-6861-2019-85-1-ii-82-85.

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It has been shown that «Grand» spectrometers based on a hybrid assembly of BLPP-2000 photodetector arrays produced by «VMK-Optoélektronika» can be used for atomic emission spectral analysis of solutions using inductively coupled plasma atomic emission spectroscopy (ICP-AES). For the prototype of a «Grand-ICP» spectrometer consisting of «Grand» spectrometer, microwave plasma generator, and RF (radiofrequency) generator, the following analytical characteristics were determined: element detection limit, long-term stability, linear ranges of calibration graphs for several elements, and optimal operating parameters of the microwave generator. The linear concentration range of analyte elements is 105when using a single analytical line of the element. The long-term stability is less than 2% in 6 h without using an internal standard. The detection limits are comparable to those of modern ICP spectrometers with an axial plasma survey and lie in a range of sub-microgram per liter. It has been found that the effect of superposition of the spectral lines of the plasma background, for example, OH molecular lines or others, on the analyte lines can be eliminated by subtracting the blank sample spectrum from the analyte spectrum using Atom software. The analytical characteristics of the spectrometer allow the use of the device both for developing new ICP- based systems and restoring the performance of defective ICP spectrometers.

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Markert, T. H. „Dispersive Spectroscopy on AXAF“. International Astronomical Union Colloquium 115 (1990): 339–45. http://dx.doi.org/10.1017/s0252921100012550.

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AbstractThere are two transmission grating spectrometers and one Bragg crystal spectrometer being developed for the Advanced X-ray Astrophysics Facility (MIT is building the crystal spectrometer and one of the grating spectrometers; the Laboratory for Space Research in Utrecht is responsible for the other grating spectrometer). The gratings divide the AXAF energy band (80 eV – 10 keV) into three regions (the MIT instrument contains gratings with two different periods) and attain resolving powers for point sources between 100 and 1800. The gratings are composed of arrays of small facets mounted on plates which can be inserted immediately behind the AXAF telescope. The dispersed spectra from the grating arrays are read out by one of the AXAF imaging instruments.The Bragg Crystal Spectrometer (BCS) is a focal plane instrument. One of eight selectable curved diffractors intercepts the AXAF X-ray beam as it diverges beyond the focal point X-rays that satisfy Bragg’s law are reflected from the crystal which, because of its curvature, re-focuses the beam onto an imaging detector. Narrow spectral regions are scanned by rocking the crystal over a range ~0.1 to 1°. Nearly the entire AXAF energy range can be studied by selecting the appropriate crystal and rotating it to the proper Bragg angle. The BCS achieves the highest spectral resolutions of the AXAF spectrometers: for 500 eV < E < 1600 eV, the FWHM of a narrow line (ΔE) is ≲ 1 eV.

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Tadic, T., Y. Mokuno, Y. Horino und M. Jaksic. „GEOMETRICAL ABERRATIONS IN THE VON HAMOS AND THE PLANE BRAGG CRYSTAL SPECTROMETERS“. International Journal of PIXE 07, Nr. 03n04 (Januar 1997): 117–33. http://dx.doi.org/10.1142/s0129083597000151.

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Numerical calculations of the effect of the finite dimensions and orientations of source and crystal are presented for plane and von Hamos Bragg crystal spectrometers for PIXE analysis, combined with a position sensitive (X-ray) detector. Analytical studies of all effects are provided. It is shown that some parameters can produce line shifts and asymmetries. A numerical model for an X-ray diffraction ray-tracing procedure for a crystal Bragg spectrometer is described.

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Schröder, H. Fr. „Polar Organic Pollutants on Their Way from Waste Water to Drinking Water“. Water Science and Technology 25, Nr. 11 (01.06.1992): 241–48. http://dx.doi.org/10.2166/wst.1992.0298.

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The examination of pollutants in waste-, surface- and drinking water by sum parameters like COD, BOD or TOC gives no information about their toxicity or behaviour in the drinking water treatment process. As many pollutants leaving sewage treatment plants are polar and/or thermolabile, gas Chromatographic (GC) separation coupled on-line with a mass spectrometer (MS) is not applicable to this problem. Newly established analytical methods like high performance liquid chromatography (HPLC) in on-line combination with mass- (MS) or tandem mass spectrometers (MS/MS) using soft ionization techniques like thermospray (TSP) would help to solve these problems. The comparison of GC- and LC/MS-spectra demonstrates increasing polarity beginning at the waste water treatment and ending at the drinking water treatment. It was possible to identify and quantify selected compounds, and elimination efficiency could be reviewed by comparing overview spectra. The knowledge about the existence of these compounds in waste-, surface- and drinking water requires strategies for elimination, avoidance or degradation.

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Groitl, Felix, Thomas Keller und Klaus Habicht. „Generalized resolution matrix for neutron spin-echo three-axis spectrometers“. Journal of Applied Crystallography 51, Nr. 3 (29.05.2018): 818–30. http://dx.doi.org/10.1107/s1600576718005307.

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This article describes the energy resolution of spin-echo three-axis spectrometers (SE-TASs) by a compact matrix formalism. SE-TASs allow one to measure the line widths of elementary excitations in crystals, such as phonons and magnons, with an energy resolution in the µeV range. The resolution matrices derived here generalize prior work: (i) the formalism works for all crystal structures; (ii) spectrometer detuning effects are included; these arise typically from inaccurate knowledge of the excitation energy and group velocity; (iii) components of the gradient vector of the dispersion surface dω/dq perpendicular to the scattering plane are properly treated; (iv) the curvature of the dispersion surface is easily calculated in reciprocal units; (v) the formalism permits analysis of spin-echo signals resulting from multiple excitation modes within the three-axis spectrometer resolution ellipsoid.

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Roy, Simon A., Simon Potvin, Jérôme Genest und Raphaël Desbiens. „Fast line-shape correction procedure for imaging Fourier-transform spectrometers“. Applied Optics 46, Nr. 21 (06.07.2007): 4674. http://dx.doi.org/10.1364/ao.46.004674.

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Ramsey, Jeremy, Srikanth Ranganathan, Richard L. McCreery und Jun Zhao. „Performance Comparisons of Conventional and Line-Focused Surface Raman Spectrometers“. Applied Spectroscopy 55, Nr. 6 (Juni 2001): 767–73. http://dx.doi.org/10.1366/0003702011952460.

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Pupyshev, A. A. „Spectral interferences and their correction in atomic emission spectral analysis“. Industrial laboratory. Diagnostics of materials 85, Nr. 1II) (15.02.2019): 15–32. http://dx.doi.org/10.26896/1028-6861-2019-85-1-ii-15-32.

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The main sources of spectral interferences in atomic emission spectral analysis (AESA) are considered, including both wide-range (bremsstrahlung and recombination continuum, radiation of hot condensed particles and electrode ends, scattered light in the spectrometer, overlapping of the analytical line by the wings of the neighbor strong spectral lines of interfering elements, imposition of the components of molecular bands with the very close lines) and narrow-band (partial or complete overlapping of the analytical line with atomic or ionic lines of the sample elements, electrodes and discharge atmosphere; superposition of spectra from higher orders of reflection in conventional diffraction spectrometers and from neighboring orders in two-dimensional echelle spectrometers). The features of their manifestation in various sources of spectrum excitation (flames, DC arc, spark discharges, arc plasma discharges, inductively coupled plasma, microwave plasma, low-pressure electric discharges, laser spark) are considered. The possibilities of reducing the level of spectral interferences or elimination of the spectral noise at the stage of design and manufacturing of AESA devices, as well as upon selecting and adjusting of operation conditions of the analysis are shown. Much attention is paid to the most easily implemented in practice off-peak correction of wide-range spectral interferences. The modern methods of background correction under the spectral peak (under-peak) using a software for atomic emission spectrometers and providing creation of various mathematical models of the background signal in the vicinity of the analytical line at the stage of developing a specific AESA technique are considered. The issues of the choice of spectral lines for analytical measurements, tables and atlases of spectral lines, electronic databases used for this purpose are considered in detail. Specific features of application of the method of inter-element correction with direct spectral overlapping of the lines are given. The operating sequence for taking into account spectral interferences when developing the analysis techniques is proposed.

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Nishimura, Atsushi, Takeru Matsumoto, Teppei Yonetsu, Yuka Nakao, Shinji Fujita, Hiroyuki Maezawa, Toshikazu Onishi und Hideo Ogawa. „Observational demonstration of a low-cost fast Fourier transform spectrometer with a delay-line-based ramp-compare ADC implemented on FPGA“. Publications of the Astronomical Society of Japan 73, Nr. 3 (07.05.2021): 692–700. http://dx.doi.org/10.1093/pasj/psab030.

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Abstract In this study, a novel type of Fourier transform radio spectrometer (termed as all-digital radio spectrometer; ADRS) has been developed in which all functionalities comprising a radio spectrometer including a sampler and Fourier computing unit were implemented as a soft-core on a field-programmable gate array (FPGA). A delay-line-based ramp-compare analog-to-digital converter (ADC), which was completely digital, was used, and two primary elements of the ADC, an analog-to-time converter (ATC) and a time-to-digital converter (TDC), were implemented on the FPGA. The sampling rate of the ADRS f and the quantization bit rate n are limited by the relation τ = 1/(2nf), where τ is the latency of the delay element of the delay-line. Given that the typical latency of the delay element implemented on FPGAs is ∼10 ps, the adoption of a low-quantization bit rate, which satisfies the requirements for radio astronomy, facilitates the realization of a high sampling rate up to ∼100 GSa s−1. In addition, as the proposed ADRS does not require a discrete ADC and can be implemented on mass-produced evaluation boards, its fabrication cost is much lower than that of conventional spectrometers. The ADRS prototype was fabricated with values of f = 600 MSa s−1 and n = 6.6 using a PYNQ-Z1 evaluation board, with a τ of 16.7 ps. The performance of the prototype, including its linearity and stability, was measured, and a test observation was conducted using the Osaka Prefecture University 1.85−m mm–submm telescope; this confirmed the potential application of the prototype in authentic radio observations. With a cost performance 10 times better (∼800 USD GHz−1) than conventional radio spectrometers, the prototype facilitates cost-effective coverage of intermediate frequency bandwidths of ∼100 GHz in modern receiver systems.

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Torrisi, Lorenzo, Giuseppe Costa, Giovanni Ceccio, Antonino Cannavò, Nancy Restuccia und Mariapompea Cutroneo. „Magnetic and electric deflector spectrometers for ion emission analysis from laser generated plasma“. EPJ Web of Conferences 167 (2018): 03011. http://dx.doi.org/10.1051/epjconf/201816703011.

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The pulsed laser-generated plasma in vacuum and at low and high intensities can be characterized using different physical diagnostics. The charge particles emission can be characterized using magnetic, electric and magnet-electrical spectrometers. Such on-line techniques are often based on time-of-flight (TOF) measurements. A 90° electric deflection system is employed as ion energy analyzer (IEA) acting as a filter of the mass-to-charge ratio of emitted ions towards a secondary electron multiplier. It determines the ion energy and charge state distributions. The measure of the ion and electron currents as a function of the mass-to-charge ratio can be also determined by a magnetic deflector spectrometer, using a magnetic field of the order of 0.35 T, orthogonal to the ion incident direction, and an array of little ion collectors (IC) at different angles. A Thomson parabola spectrometer, employing gaf-chromix as detector, permits to be employed for ion mass, energy and charge state recognition. Mass quadrupole spectrometry, based on radiofrequency electric field oscillations, can be employed to characterize the plasma ion emission. Measurements performed on plasma produced by different lasers, irradiation conditions and targets are presented and discussed. Complementary measurements, based on mass and optical spectroscopy, semiconductor detectors, fast CCD camera and Langmuir probes are also employed for the full plasma characterization. Simulation programs, such as SRIM, SREM, and COMSOL are employed for the charge particle recognition.

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Strocov, V. N., T. Schmitt, U. Flechsig, L. Patthey und G. S. Chiuzbăian. „Numerical optimization of spherical variable-line-spacing grating X-ray spectrometers“. Journal of Synchrotron Radiation 18, Nr. 2 (29.01.2011): 134–42. http://dx.doi.org/10.1107/s0909049510054452.

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McComb, Mark E., Lynda J. Donald und Hélène Perreault. „Electrospray ionization mass spectrometry and on-line capillary zone electrophoresis - mass spectrometry for the characterization of citrate synthase“. Canadian Journal of Chemistry 77, Nr. 11 (01.11.1999): 1752–60. http://dx.doi.org/10.1139/v99-138.

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The enzyme citrate synthase from E. coli is a protein with a molecular weight (Mr) of 47 885 Da (wild type). This enzyme has been studied extensively, and its amino acid sequence has been characterized. This model protein has been used in this work for development and validation of methods involving capillary electrophoresis (CE) and electrospray ionization mass spectrometry (ESI-MS). The Mr determinations were conducted using sample infusion ESI-MS, and the tryptic digestion products of wild-type citrate synthase were characterized by on-line CE-ESI-MS coupled with a sheathless interface. On-line experiments were conducted on two different mass spectrometers, a Quattro-LC triple quadrupole instrument equipped with a Z-SprayTM source (Micromass), and a reflecting time-of-flight (TOF) mass spectrometer built in-house in the Time-of-Flight Laboratory, Department of Physics, University of Manitoba. This is the first article to be written on the interfacing of a Z-SprayTM source with CE. Unmodified fused silica capillaries gold-coated sheathless interfaces were used. The on-line CE separations yielded theoretical plate numbers greater than 104 on average. Selected ion electrophorograms (SIE) of the tryptic peptides recorded on the Quattro-LC displayed S/N ratios ranging from ca. 14 to 120 on raw data. These SIE enabled identification of each peptide. The use of reflecting time-of-flight mass spectrometry (TOFMS) afforded mass resolution values of ca. 6000 (m/deltamFWHM), which enabled isotopic resolution of the peptide components. CE-ESI-MS and CE-ESI-TOFMS experiments enabled the generation of a complete tryptic map of citrate synthase.Key words: capillary electrophoresis, electrospray ionization, mass spectrometry, citrate synthase, tryptic digestion, triple quadrupole analyzer, time-of-flight analyzer.

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Torres, A., und J. L. Bertrand-Krajewski. „Partial Least Squares local calibration of a UV–visible spectrometer used for in situ measurements of COD and TSS concentrations in urban drainage systems“. Water Science and Technology 57, Nr. 4 (01.03.2008): 581–88. http://dx.doi.org/10.2166/wst.2008.131.

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Recent UV–visible spectrometers deliver on line and in situ absorbance spectra in wastewater or stormwater transported in urban drainage systems. After calibration with local data sets, spectra can be used to estimate pollutant concentrations. Calibration methods are usually based on PLS (Partial Least Squares) regression. Their most important difficulty lies in the identification of the number of both i) the latent vectors and ii) the independent variables. A method is proposed to identify these variables, based on an exhaustive tests procedure (Jackknife cross validation and matrix of prediction indicator). It was applied to estimate TSS (total suspended solids) or COD (chemical oxygen demand) concentrations at the inlet of a storage-settling tank in a stormwater separate sewer system, and compared to three other calibration methods used either for turbidity meters or UV–visible spectrometers. With the available calibration data set: i) the spectrometer gives results with better prediction quality than the turbidity meter, ii) for the spectrometer, local calibration gives better results than global calibration, iii) the proposed PLS method gives results with a similar order of magnitude in uncertainties as the manufacturer local calibration method, but is more open and transparent for the user. Similar results were obtained for a second data set.

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Kapitanov, Venedikt A., Alexander M. Solodov, Tatiana M. Petrova und Yurii N. Ponomarev. „Fourier Transform and Photoacoustic Absorption Spectra of Ethylene within 6035–6210 cm-1: Comparative Measurements“. International Journal of Spectroscopy 2010 (01.06.2010): 1–6. http://dx.doi.org/10.1155/2010/203672.

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Measurements of ethylene absorption spectra with Fourier Transform (FT) and Photoacoustic (PA) spectrometers within 6035–6210 cm−1 are described. The methodology used for building the frequency scale for both spectrometers is presented. The methane absorption spectrum, included into the HITRAN database, was used in both cases to calibrate the frequency scale. Ethylene absorption spectra were obtained with the two recording methods; a coincidence of the measured line center positions was obtained with an accuracy of 0.0005 cm−1.

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Tang, Xiaojun, Wenjing Wang, Xuliang Zhang, Erzhen Wang und Xuanjiannan Li. „On-Line Analysis of Oil-Dissolved Gas in Power Transformers Using Fourier Transform Infrared Spectrometry“. Energies 11, Nr. 11 (17.11.2018): 3192. http://dx.doi.org/10.3390/en11113192.

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To address the problem of on-line dissolved gas analysis (DGA) of a power transformer, a Fourier transform infrared (FT-IR) spectrometer was used to develop an analysis instrument. Carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), ethane (C2H6), ethylene (C2H4) and acetylene (C2H2) were the analytes for the FT-IR spectrometer while propane (C3H8), propylene (C3H6), propyne (C3H4), n-butane (n-C4H10) and iso-butane (iso-C4H10) were the interferents, which might exist in the dissolved gas but are not currently used as analytes for detecting an internal fault. The instrument parameters and analysis approach are first introduced. Specifically, an absorption spectra reading approach by switching two cone-type gas cells into separate light-paths was presented for reducing the effects of gas in the gaps between gas cells and spectrometers, scanning the background spectrum without clearing the sample cell, and increasing the dynamics. Then, the instrument was tested with a standard gas mixture that was extracted from insulation oil in a power transformer. The testing results show that the detection limit of every analyte component is lower than 0.1 μL/L, and the detection limits of all analytes meet the detection requirements of oil-dissolved gas analysis, which means that the FT-IR spectrometer may be an ideal instrument due to its benefits, such as being maintenance-free and having a high stability.

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Fulton, Greg, und Gary Horlick. „Aotfs as Atomic Spectrometers: Basic Characteristics“. Applied Spectroscopy 50, Nr. 7 (Juli 1996): 885–92. http://dx.doi.org/10.1366/0003702963905475.

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An electronic spectrometer based on an acousto-optic tunable filter (AOTF) is presented. These devices are electronically tunable, narrow-band light filters with no moving parts. The wavelength range from 350 to 600 nm can be covered with a single device, the entire spectrum is scanned in less than 1 s, and any wavelength can be randomly accessed in 0.1 ms. The resolution [full width at half-height (FWHH)] was determined to be 0.22 nm at 361 nm, and the standard deviation of peak position was usually less than 0.03 nm. Under software control, the AOTF can be stationary on a line, peak-hop between any 20 different lines, hop between 20 regions of any size, scan a spectrum, or operate as a wavelength modulation spectrometer. Operation of the spectrometer is illustrated by using hollow cathode and inductively coupled plasma atomic emission sources.

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Luo, Biao, Zhi Yu Wen, Hai Tao Liu, Li Chen und Rong Rong Qian. „A Novel Micro Mirror Spectrometer and Test Experiment“. Key Engineering Materials 503 (Februar 2012): 266–71. http://dx.doi.org/10.4028/www.scientific.net/kem.503.266.

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In order to realize more compact and in particular cost-effective spectrometers MOEMS technology offers attractive possibilities. Based Littrow spectrometer structure for the near-IR, a micro mirror grating spectrometer has been designed and developed. The ZEMAX was used for designed this structure. The resolution of this design is 10nm, the spectral range from 900nm to 1400nm. A scanning micro mirror is the key element of this IR spectrometer set-up. This micro mirror is driven by electromagnetic force. Before fix the micro mirror, it was calibrated. Meanwhile, for reducing the cost of this system, the silicon silt was designed and fabricated. For resolution testing of this spectral system, we used one light correction filters finished this experiment. The test result has shown the resolution of this spectrometer is16.8nm. Finally, the relation between the spectral line scanning characteristic and wavelength spectral resolution was discussed.

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Alvisi, Marco, Markus Blome, Michael Griepentrog, Vasile-Dan Hodoroaba, Peter Karduck, Marco Mostert, Michele Nacucchi et al. „The Determination of the Efficiency of Energy Dispersive X-Ray Spectrometers by a New Reference Material“. Microscopy and Microanalysis 12, Nr. 5 (19.09.2006): 406–15. http://dx.doi.org/10.1017/s1431927606060557.

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A calibration procedure for the detection efficiency of energy dispersive X-ray spectrometers (EDS) used in combination with scanning electron microscopy (SEM) for standardless electron probe microanalysis (EPMA) is presented. The procedure is based on the comparison of X-ray spectra from a reference material (RM) measured with the EDS to be calibrated and a reference EDS. The RM is certified by the line intensities in the X-ray spectrum recorded with a reference EDS and by its composition. The calibration of the reference EDS is performed using synchrotron radiation at the radiometry laboratory of the Physikalisch-Technische Bundesanstalt. Measurement of RM spectra and comparison of the specified line intensities enables a rapid efficiency calibration on most SEMs. The article reports on studies to prepare such a RM and on EDS calibration and proposes a methodology that could be implemented in current spectrometer software to enable the calibration with a minimum of operator assistance.

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Watanabe, Yoshimasa, Yutaro Chiba, Takeshi Sakai, Akemi Tamanai, Rikako Suzuki und Nami Sakai. „Spectrometer Using superconductor MIxer Receiver (SUMIRE) for laboratory submillimeter spectroscopy“. Publications of the Astronomical Society of Japan 73, Nr. 2 (09.02.2021): 372–93. http://dx.doi.org/10.1093/pasj/psab005.

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Abstract Recent spectroscopic observations by sensitive radio telescopes require accurate molecular spectral line frequencies to identify molecular species in a forest of lines detected. To measure rest frequencies of molecular spectral lines in the laboratory, an emission-type millimeter and submillimeter-wave spectrometer utilizing state-of-the-art radio-astronomical technologies is developed. The spectrometer is equipped with a 200 cm glass cylinder cell, a two-sideband (2SB) superconductor-insulator-superconductor (SIS) receiver in the 230 GHz band, and wide-band auto-correlation digital spectrometers. By using the four 2.5 GHz digital spectrometers, a total instantaneous bandwidth of the 2SB SIS receiver of 8 GHz can be covered with a frequency resolution of 88.5 kHz. Spectroscopic measurements of CH3CN and HDO are carried out in the 230 GHz band so as to examine the frequency accuracy, stability, sensitivity, as well as the intensity calibration accuracy of our system. As for the result of CH3CN, we confirm that the frequency accuracy for lines detected with sufficient signal-to-noise ratio is better than 1 kHz, when the high-resolution spectrometer having a channel resolution of 17.7 kHz is used. In addition, we demonstrate the capability of this system by spectral scan measurement of CH3OH from 216 GHz to 264 GHz. We assign 242 transitions of CH3OH, 51 transitions of 13CH3OH, and 21 unidentified emission lines for 295 detected lines. Consequently, our spectrometer demonstrates sufficient sensitivity, spectral resolution, and frequency accuracy for in-situ experimental-based rest frequency measurements of spectral lines for various molecular species.

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Poletto, Luca, und Roger J. Thomas. „Stigmatic spectrometers for extended sources: design with toroidal varied-line-space gratings“. Applied Optics 43, Nr. 10 (01.04.2004): 2029. http://dx.doi.org/10.1364/ao.43.002029.

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Ziurys, L. M. „Spectral-Line Surveys at Millimeter and Submillimeter Wavelengths: Impact of Spectral Resolution“. Highlights of Astronomy 13 (2005): 825–27. http://dx.doi.org/10.1017/s1539299600017251.

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AbstractMillimeter and submillimeter astronomy has achieved very high spectral resolution (λ/Δλ ≥ 106-107) over the past 20 years. Broad-band spectral-line surveys at these wavelengths have only taken partial advantage of these capabilities. Such surveys could be more effective with an increase in spectral resolution, accompanied by improvement in the stability and bandwidth of spectrometers and the employment of single-sideband detectors.

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Vickers, Thomas J., Christopher A. Rosen und Charles K. Mann. „Compact Raman Spectrometers: Data Handling Methods“. Applied Spectroscopy 50, Nr. 8 (August 1996): 1074–81. http://dx.doi.org/10.1366/0003702963905222.

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Measurements have been made on a compact dispersive Raman spectrometer of the type often proposed for on-line measurements. Quantitative use of the details of spectra that are produced by this system require different data treatments than those which have been described for longer-focal-length instruments. The data sets are sparsely sampled, and they cover a wide spectral window. Owing to sparse sampling, spectra as recorded have the appearance of piecewise linear approximations. It is necessary to interpolate additional data points in order to observe details of peaks, such as exact positions of maxima. With wider spectral windows, procedures for calibration of the wavenumber axis which have been previously described do not meet our performance criterion: an accuracy of 0.1 cm−1 or better. A model that involves a fifth-order polynomial is needed. On the basis of the performance of this model, atomic lines which give satisfactory results when used as wavenumber references have been identified. Details of a self-modeling procedure for removal of broad-band spectral interferences are described, and its performance is demonstrated.

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Rogers, Alan E. E., Philip J. Erickson, Larisa P. Goncharenko, Omar B. Alam, John Noto, Robert B. Kerr und Sudha Kapali. „Seasonal and Local Solar Time Variation of the Meridional Wind at 95 km from Observations of the 11.072-GHz Ozone Line and the 557.7-nm Oxygen Line“. Journal of Atmospheric and Oceanic Technology 33, Nr. 7 (Juli 2016): 1355–61. http://dx.doi.org/10.1175/jtech-d-15-0247.1.

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AbstractGround-based spectrometers have been deployed to measure the concentration, velocity, and temperature of ozone in the mesosphere and lower thermosphere (MLT), using low-cost satellite television electronics to observe the 11.072-GHz line of ozone. The ozone line was observed at an altitude near 95 km at 38°N, 71°W using three spectrometers located at the Massachusetts Institute of Technology’s Haystack Observatory (Westford, Massachusetts), Chelmsford High School (Chelmsford, Massachusetts), and Union College (Schenectady, New York), each pointed south at 8° elevation. Observations from 2009 through 2014 were used to derive the nightly averaged seasonal variation of the 95-km altitude meridional wind velocity, as well as the seasonally averaged variation of the meridional wind with local solar time. The results indicate a seasonal trend in which the winds at 95 km are directed southward at about 10 m s−1 in the summer of the Northern Hemisphere and northward at about 10 m s−1 in the winter. Nighttime data from −5 to +5 local solar time show a gradual transition of the meridional wind velocity from about −20 to 20 m s−1. These variations correlate well with nighttime wind measurements using 557.7-nm optical airglow observations from the Millstone Hill high-resolution Fábry–Perot interferometer (FPI) in Westford.

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TOKUSHIMA, T., Y. HARADA, M. WATANABE, Y. TAKATA, E. ISHIGURO, A. HIRAYA und S. SHIN. „DESIGN OF A FLAT FIELD SPECTROMETER FOR SOFT X-RAY EMISSION SPECTROSCOPY“. Surface Review and Letters 09, Nr. 01 (Februar 2002): 503–8. http://dx.doi.org/10.1142/s0218625x02002567.

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A spectrometer for soft X-ray emission spectroscopy was designed and constructed. The aims of this spectrometer are high detection efficiency and realizing the energy resolution of 1000 (E/ΔE) in a compact size. To satisfy these requirements, a flat field spectrometer with a varied line spacing grating and a CCD detector was chosen. Furthermore, the configuration without the entrance slit was employed. For compact flat field spectrometers, the spectral dispersion on the detector is sometimes smaller than the spatial resolution of existing detectors restricting maximum energy resolution. The spectral dispersion on the detector was optimized to balance with the spatial resolution of CCD. Optical performance was tested with a ray-tracing program. The spectrometer covers 250–900 eV, with two gratings. Taking into account the spatial resolution of a CCD detector, the maximum energy resolution of the spectrometer is estimated to be about 1000 (E/ΔE) for the beam size of 10 μm. Using the constructed spectrometer, test experiments were performed at the beamline BL27SU in SPring-8.

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Lopez-Avila, Viorica, Richard Young, Robert Kim, Werner F. Beckert, M. Bruce, P. David, S. Eckert-Tilotta et al. „Interiaboratory Evaluation of an Off-Line Supercritical Fluid Extraction/Infrared Spectrometric Method for Determination of Petroleum Hydrocarbons in Solid Matrixes“. Journal of AOAC INTERNATIONAL 76, Nr. 3 (01.05.1993): 555–64. http://dx.doi.org/10.1093/jaoac/76.3.555.

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Abstract A collaborative study was conducted, with 14 laboratories participating, to determine the method accuracy and precision of the proposed U.S. Environmental Protection Agency Methods 3560 and 8440. These methods involve the extraction of petroleum hydrocarbons from solid matrixes with supercritical carbon dioxide at 340 atm and 80°C for 30 min (dynamic), collection of the extracted materials in tetrachloroethene (Method 3560), and analysis of the extracts by infrared (IR) spectrometry (Method 8440). The study design was based on the AOAC blind replicate design with balanced replicates. The study samples consisted of 4 solid matrixes that had petroleum hydrocarbon contents ranging from 614 to 32 600 mg/kg. Each of the 4 matrixes was extracted in triplicate, and the extracts were analyzed with 2 different IR spectrometers. In addition, each of the participating laboratories extracted a sample of unspiked clay soil, the same clay soil spiked with corn oil and reference oil at 1000 mg/kg each, and the same clay soil wetted to 30% water content and spiked with motor oil at 10 000 mg/kg (the latter 3 samples were extracted only once). Results indicated that the overall method accuracy for concentrations ranging from 614 to 32 600 mg/kg was 82.9%; the mean recoveries of petroleum hydrocarbons for each of the 4 solid matrixes ranged from 77.9 to 107% for analyses performed with the Perkin-Elmer Fourier transform IR spectrometer and from 75.9 to 101% for analyses performed with the Buck-Scientific IR spectrometer; the differences between the 2 instruments on a sample-bysample basis were less than 17% for the total petroleum hydrocarbon determinations. The interiaboratory method precisions (RSDR) appeared to be matrix-dependent and ranged from 17.3 to 45.4% for analyses performed with the Perkin- Elmer Fourier transform IR spectrometer and from 16.7 to 47.9% for the Buck-Scientific IR spectrometer. The intralaboratory method precisions (RSDr) appeared to be less matrix-dependent and ranged from 11.5 to 17.0% for analyses performed with the Perkin-Elmer FTIR spectrometer and from 11.1 to 18.2% for the Buck-Scientific IR spectrometer. Method accuracy and precision data are also presented for the 5 laboratories that used Isco supercritical fluid extraction systems and for the 7 laboratories that used vessels with volumes of 3.5 mL or less with different supercritical fluid extraction systems.

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Cui, Lin-Lin, und Xu Wang. „Determination of carbon and oxygen isotopes of geological samples with a complicated matrix: comparison of different analytical methods“. Anal. Methods 6, Nr. 22 (2014): 9173–78. http://dx.doi.org/10.1039/c4ay01717j.

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Several automated on-line carbonate reaction devices coupled with isotope ratio mass spectrometers (IRMS) have been frequently used to determine the isotopic compositions of the carbon and oxygen in carbonates because of their high efficiency and small sample size.

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Quyen, Nguyen The, Edouard Da Silva, Nguyen Quy Dao und Michel D. Jouan. „New Raman Spectrometer Using a Digital Micromirror Device and a Photomultiplier Tube Detector for Rapid On-Line Industrial Analysis. Part I: Description of the Prototype and Preliminary Results“. Applied Spectroscopy 62, Nr. 3 (März 2008): 273–78. http://dx.doi.org/10.1366/000370208783759704.

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In this paper, a prototype of a new generation of Raman spectrometers, based on the use of a monochromator, a digital micromirror device as light modulator, and a photomultiplier tube as detector of the Raman light, is described. This spectrometer, containing no moving parts, is inexpensive, robust, and very precise. New in concept, this spectrometer makes it possible to record, in addition to classical Raman spectra, the intensity at several selected points of the spectrum and/or the total intensity in several selected intervals at the same time with great accuracy, thus giving new possibilities for analytical applications. Also, the work presented demonstrates the possibilities of this very simple prototype for rapid on-line industrial analysis, with an example of quantitative analysis of binary and ternary mixtures of xylene isomers. The precision obtained is satisfactory (errors of prediction ∼3% in 5–6 seconds per sample).

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Genest, Jérôme, und Pierre Tremblay. „Impact of the optical aberrations on the line shape of Fourier-transform spectrometers“. Vibrational Spectroscopy 29, Nr. 1-2 (Juli 2002): 3–13. http://dx.doi.org/10.1016/s0924-2031(01)00171-0.

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Li, Zi Qiang, Jing Tao Ma, Xiao Xue Liu und Bing Liu. „Characterization of the Tracer YSZ/CoO Microspheres with YSZ Ceramic Coating for HTR Fuel Element“. Key Engineering Materials 697 (Juli 2016): 822–25. http://dx.doi.org/10.4028/www.scientific.net/kem.697.822.

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The Co element was used during the first operation of high temperature reactor (HTR) reactor to distinguish low-enrichment and high-enrichment fuel elements. In this paper the YSZ/CoO ceramic tracer microspheres with YSZ coating were prepared. The design size of the microspheres were about 750μm. The YSZ shell thickness were 100 μm, the mean nuclear roundness were ≤1.03 and the density were ≥5.50g/cm3. Morphology, microstructure and element composition of the core-shell microspheres were characterized by stereo microscope, scanning electron microscopy, x-ray spectrometers etc. The results of both line scan and spot scan of X-ray spectrometer show that dense YSZ shell can efficiently prevent Co element in YSZ/CoO core from diffusing into the YSZ shell at high temperature.

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Fujita, J., S. Morita und M. Sakurai. „X-ray diagnostics for fusion plasmas“. Laser and Particle Beams 7, Nr. 3 (August 1989): 483–86. http://dx.doi.org/10.1017/s0263034600007448.

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We have developed medium and high resolution X-ray crystal spectrometers for measurements of charge state distributions of impurity ions, density of suprathermal electrons and ion temperature in magnetically confined plasmas. The techniques utilizing these spectrometers are, in principle, applicable to laser produced plasmas, especially in their expanding phase. The role of X-ray spectroscopy to produce useful data for atomic physics as well as for plasma diagnostics is emphasized. A beam-line has been designed and installed to the Ultraviolet Synchrotron Radiation Facility (UVSOR) at IMS, Okazaki, for the purpose of establishing calibration techniques for optical components, detectors and spectrometers in the range from ultraviolet to soft X ray for plasma diagnostics. Characteristics of the beam and its application to the study of interaction between synchrotron radiation and hot dense plasmas are described. Synchrotron radiation can replace the dye laser which has so far been used as a light source in the laser-induced fluorescence method to obtain population density of specified levels in a plasma.

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Fountain, Augustus W., Thomas J. Vickers und Charles K. Mann. „Factors That Affect the Accuracy of Raman Shift Measurements on Multichannel Spectrometers“. Applied Spectroscopy 52, Nr. 3 (März 1998): 462–68. http://dx.doi.org/10.1366/0003702981943699.

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Raman shift measurements have been made on cyclohexane, by using linear interpolation between bracketing neon line positions to establish Raman band wavelengths. Factors that affect the precision of these measurements have been examined in detail. These include change of slit width, grating line spacing, neon line intensity, distance of separation of neon lines, and effects of small grating movements. All these have some effect, but the last factor is particularly important. Techniques that give standard deviations of 0.03 cm−1 when measurements are made without moving the grating are degraded by about an order of magnitude when the grating is moved. This result is attributed to adventitious partitioning of signal power between adjacent detector elements. By deliberately moving the grating a small amount between otherwise replicate measurements, one can control this effect. Values for the Raman shifts for eleven cyclohexane bands, based on approximately 800 Raman spectra and an equal number of neon emission spectra, are presented. The values are compared with previous measurements. They are generally within the ±σ range of the earlier values, but the standard deviations of these results are about an order of magnitude smaller.

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Sun, Kang, Xiong Liu, Caroline R. Nowlan, Zhaonan Cai, Kelly Chance, Christian Frankenberg, Richard A. M. Lee, Randy Pollock, Robert Rosenberg und David Crisp. „Characterization of the OCO-2 instrument line shape functions using on-orbit solar measurements“. Atmospheric Measurement Techniques 10, Nr. 3 (10.03.2017): 939–53. http://dx.doi.org/10.5194/amt-10-939-2017.

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Abstract. Accurately characterizing the instrument line shape (ILS) of the Orbiting Carbon Observatory-2 (OCO-2) is challenging and highly important due to its high spectral resolution and requirement for retrieval accuracy (0. 25 %) compared to previous spaceborne grating spectrometers. On-orbit ILS functions for all three bands of the OCO-2 instrument have been derived using its frequent solar measurements and high-resolution solar reference spectra. The solar reference spectrum generated from the 2016 version of the Total Carbon Column Observing Network (TCCON) solar line list shows significant improvements in the fitting residual compared to the solar reference spectrum currently used in the version 7 Level 2 algorithm in the O2 A band. The analytical functions used to represent the ILS of previous grating spectrometers are found to be inadequate for the OCO-2 ILS. Particularly, the hybrid Gaussian and super-Gaussian functions may introduce spurious variations, up to 5 % of the ILS width, depending on the spectral sampling position, when there is a spectral undersampling. Fitting a homogeneous stretch of the preflight ILS together with the relative widening of the wings of the ILS is insensitive to the sampling grid position and accurately captures the variation of ILS in the O2 A band between decontamination events. These temporal changes of ILS may explain the spurious signals observed in the solar-induced fluorescence retrieval in barren areas.

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Ryde, N., H. Hartman, E. Oliva, L. Origlia, N. Sanna, M. Rainer, B. Thorsbro, E. Dalessandro und G. Bono. „Stellar population astrophysics (SPA) with the TNG“. Astronomy & Astrophysics 631 (23.10.2019): L3. http://dx.doi.org/10.1051/0004-6361/201936594.

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Context. In the advent of new infrared high-resolution spectrometers, accurate and precise atomic data in the infrared are urgently needed. Identifications, wavelengths, strengths, broadening, and hyper-fine splitting parameters of stellar lines in the near-infrared are in many cases not accurate enough to model observed spectra, and in other cases, these parameters do not even exist. Some stellar features are unidentified. Aims. The aim with this work is to identify a spectral feature at λvac = 1063.891 nm or λair = 1063.600 nm that is visible in spectra of stars of different spectral types that are observed with the GIANO-B spectrometer. Methods. The search for spectral lines to match the unidentified feature in line lists from standard atomic databases was not successful. However, by investigating the original published laboratory data, we were able to identify the feature and solve the problem. To confirm its identification, we modelled the presumed stellar line in the solar intensity spectrum and found an excellent match. Results. We find that the observed spectral feature is a stellar line originating from the 4s′–4p′ transition in S I, and that the reason for its absence in atomic line databases is a neglected air-to-vacuum correction in the original laboratory measurements from 1967 for this line only. From interpolation we determine the laboratory wavelength of the S I line to be λvac = 1063.8908 nm or λair = 1063.5993 nm, and the excitation energy of the upper level to be 9.74978 eV.

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Griffith, David W. T. „Synthetic Calibration and Quantitative Analysis of Gas-Phase FT-IR Spectra“. Applied Spectroscopy 50, Nr. 1 (Januar 1996): 59–70. http://dx.doi.org/10.1366/0003702963906627.

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A method for the quantitative analysis of gas-phase infrared spectra is described in which calibration spectra are calculated from a database of absorption line parameters rather than measured in a real spectrometer. The synthetic calibration spectra are computed with the use of the program MALT (Multiple Atmospheric Layer Transmission), including environmental (pressure, temperature, pathlength, etc.) and instrumental (resolution, line shape, wavenumber shift) effects in the calculation, so that the calculated spectra closely approximate real measured spectra. The synthetic calibration spectra are then used in quantitative analysis as if they were real spectra. In conventional laboratory studies, the method circumvents the need for time-consuming collection of large sets of laboratory calibration spectra often required when many absorbing gases must be analyzed. It is particularly useful in long open-path and solar FT-IR spectroscopy when no sample cell is available for recording calibration spectra. Examples are presented from conventional laboratory spectra in a closed-cell, open-path FT-IR spectra used to determine trace gas fluxes in an open field, and solar absorption spectroscopy using ground-based FT-IR spectrometers.

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Byrd, R. A., und F. S. Digennaro. „A Real-Time In-Line RF Pulse Sequence and Acquisition Monitor for NMR Spectrometers“. Journal of Magnetic Resonance, Series A 112, Nr. 2 (Februar 1995): 250–54. http://dx.doi.org/10.1006/jmra.1995.1040.

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Osborn, K. D., und T. A. Callcott. „Two new optical designs for soft x‐ray spectrometers using variable‐line‐space gratings“. Review of Scientific Instruments 66, Nr. 5 (Mai 1995): 3131–36. http://dx.doi.org/10.1063/1.1145541.

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Webb, Douglas P., und Eric D. Salin. „Line selection expert system for control of scanning inductively coupled plasma atomic emission spectrometers“. Journal of Analytical Atomic Spectrometry 4, Nr. 8 (1989): 793. http://dx.doi.org/10.1039/ja9890400793.

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P. Webb, Douglas, und Eric D. Salin. „An electronic aid for line selection for scanning inductively coupled plasma atomic emission spectrometers“. Spectrochimica Acta Part B: Atomic Spectroscopy 47, Nr. 14 (Dezember 1992): 1587–94. http://dx.doi.org/10.1016/0584-8547(92)80147-9.

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Mamrashev, Alexander, Fedor Minakov, Lev Maximov, Nazar Nikolaev und Pavel Chapovsky. „Correction of Optical Delay Line Errors in Terahertz Time-Domain Spectroscopy“. Electronics 8, Nr. 12 (26.11.2019): 1408. http://dx.doi.org/10.3390/electronics8121408.

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One of the key elements of terahertz time-domain spectrometers is the optical delay line. Usually it consists of a motorized translation stage and a corner reflector mounted on its top. Errors in the positioning of the translation stage lead to various distortions of the measured waveform of terahertz pulses and, therefore, terahertz spectra. In this paper, the accuracy of position measurements is improved by using an optical encoder. Three types of systematic errors are found: Increasing and periodic offsets of the translation stage position, as well as a drift of its initial position in a series of consecutive measurements. The influence of the detected errors on the measured terahertz spectra is studied and correction methods are proposed.

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Sun, Youwen, Mathias Palm, Christine Weinzierl, Christof Petri, Justus Notholt, Yuting Wang und Cheng Liu. „Technical note: Sensitivity of instrumental line shape monitoring for the ground-based high-resolution FTIR spectrometer with respect to different optical attenuators“. Atmospheric Measurement Techniques 10, Nr. 3 (13.03.2017): 989–97. http://dx.doi.org/10.5194/amt-10-989-2017.

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Abstract. The TCCON (Total Carbon Column Observing Network) and most NDACC (Network for Detection of Atmospheric Composition Change) sites assume an ideal ILS (instrumental line shape) for analysis of the spectra. In order to adapt the radiant energy received by the detector, an attenuator or different sizes of field stop can be inserted in the light path. These processes may alter the alignment of a high-resolution FTIR (Fourier transform infrared) spectrometer, and may result in bias due to ILS drift. In this paper, we first investigated the sensitivity of the ILS monitoring with respect to application of different kinds of attenuators for ground-based high-resolution FTIR spectrometers within the TCCON and NDACC networks. Both lamp and sun cell measurements were conducted after the insertion of five different attenuators in front of and behind the interferometer. The ILS characteristics derived from lamp and sun spectra are in good agreement. ILSs deduced from all lamp cell measurements were compared. As a result, the disturbances to the ILS of a high-resolution FTIR spectrometer with respect to the insertion of different attenuators at different positions were quantified. A potential strategy to adapt the incident intensity of a detector was finally deduced.

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Casian, Tibor, Alexandru Gavan, Sonia Iurian, Alina Porfire, Valentin Toma, Rares Stiufiuc und Ioan Tomuta. „Testing the Limits of a Portable NIR Spectrometer: Content Uniformity of Complex Powder Mixtures Followed by Calibration Transfer for In-Line Blend Monitoring“. Molecules 26, Nr. 4 (20.02.2021): 1129. http://dx.doi.org/10.3390/molecules26041129.

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(1) Background: Portable NIR spectrometers gain more and more ground in the field of Process Analytical Technology due to the easy on-site flexibility and interfacing versatility. These advantages that originate from the instrument miniaturization, also come with a downside with respect to performance compared to benchtop devices. The objective of this work was to evaluate the performance of MicroNIR in a pharmaceutical powder blend application, having three active ingredients and 5 excipients. (2) Methods: Spectral data was recorded in reflectance mode using static and dynamic acquisition, on calibration set samples developed using an experimental design. (3) Results: The developed method accurately predicted the content uniformity of these complex mixtures, moreover it was validated in the entire calibration range using ±10% acceptance limits. With respect to at-line prediction, the method presented lower performance compared to a previously studied benchtop spectrometer. Regarding the in-line monitoring of the blending process, it was shown that the spectral variability-induced by dynamic acquisition could be efficiently managed using spectral pre-processing. (4) Conclusions: The in-line process monitoring resulted in accurate concentration profiles, highlighting differences in the mixing behaviour of the investigated ingredients. For the low dose component homogeneity was not reached due to an inefficient dispersive mixing.

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