Search results for "spectrometer"
showing 10 items of 751 documents
Monitoring supercritical fluid extraction by thermal lens spectrometry with pulsed laser excitation
1999
Abstract A dual-beam thermal lens spectrometer (TLS) with a pulse pump–probe coaxial configuration was coupled to commercially available supercritical fluid extraction equipment using a high-pressure flow cell interface. Because of its feasible critical parameters, moderate cost and good thermooptical properties, carbon dioxide was used as supercritical solvent. Using trans -β-carotene as analyte, several factors related with the extraction process under continuos flow conditions were studied in order to establish their influence in the thermal lens signal magnitude. Under the optimum experimental conditions, the relative TLS signal area showed a linear relationship with the concentration o…
High-resolution stimulated Raman spectroscopy and analysis of the ν 1 , 2ν 1 -ν 1 , ν 2 , 2ν 2 , and 3ν 2 -ν 2 bands of CF4
2013
The spectra of the ν1, 2ν1–ν1, ν2, 2ν2, and 3ν2–ν2 bands of CF4 were obtained with a quasi-continuous wave stimulated Raman spectrometer. These five bands were studied at a temperature of 135 and 300 K (for the hot bands). The spectrum of ν1 was obtained at a sample pressure of 2 mbar. For the spectra of the other regions, which are much weaker, higher pressures were used. The analysis has been performed thanks to the xtds and spview softwares developed in Dijon for such highly symmetric molecules. Combining the present results with a previous infrared study, we could determine a very accurate value for the C–F equilibrium bond length, i.e. re = 1.31588(6) A. Copyright © 2013 John Wiley & S…
High-resolution spectroscopy of the ν3 band of WF6 and ReF6 in a supersonic jet
2002
We have recorded the Fourier-transform infrared (FTIR) spectrum of the ν3 fundamental band of WF6 in a continuous supersonic jet expansion with an instrumental bandwidth of 0.0024 cm−1 (FWHM, full width at half maximum, unapodized), using a Bomem DA.002 spectrometer. Some parts of this band have also been recorded with 0.0007 cm−1 bandwidth using a diode laser spectrometer combined with a pulsed slit jet expansion. A multiple-pass arrangement has been used for the slit jet to observe low-intensity lines. In each case, we have used a WF6:He mixture with a seeding ratio 1:3 leading to a rotational temperature of ca. 50 K. This work extends the previous investigation of Takami and Kuze [J. Che…
Liquid sample introduction in inductively coupled plasma atomic emission and mass spectrometry — Critical review
2014
Abstract Inductively coupled plasma optical emission spectroscopy (ICP-OES) and mass spectrometry (ICP-MS) can be considered as the most important tools in inorganic analytical chemistry. Huge progress has been made since the first analytical applications of the ICP. More stable RF generators, improved spectrometers and detection systems were designed along with the achievements gained from advanced microelectronics, leading to overall greatly improved analytical performance of such instruments. In contrast, for the vast majority of cases liquid sample introduction is still based on the pneumatic principle as described in the late 19th century. High flow pneumatic nebulizers typically deman…
Gas-phase detection of HSOD and empirical equilibrium structure of oxadisulfane
2006
We present the first gas phase spectra of singly deuterated oxadisulfane, HSOD, in its vibrational ground state. More than 100 transitions have been recorded with highest frequency accuracy using the Cologne Terahertz Spectrometer. The molecular parameters derived from a least squares fit analysis proof HSOD to be an almost accidental symmetric prolate top molecule with an asymmetry parameter kZK0.9985. Spectra of c-type and weaker b-type transitions have been recorded in the range from 716 to 772 GHz. The ratio of the dipole moments mc/mbZ2.4(3) has been derived from measured line intensities. The c-type transitions are split by the tunneling motion of a hindered internal rotation, whereas…
Potential retrieval of biophysical parameters from FLORIS, S3-OLCI and its synergy
2012
The main objective of FLEX is the measurement of vegetation chlorophyll fluorescence (Fs) from space and the exploitation of this signal to better understand the carbon cycle. FLuORescence Imaging Spectrometer (FLORIS) is the main instrument of the FLEX mission concept. ESA's Earth Science Advisory Committee recommended the investigation of the FLEX concept as an in-orbit demonstrator to be flown as a tandem mission with Sentinel-3 (S-3). S-3 is amongst others equipped with the Ocean Land Colour Instrument (OLCI). When flown in tandem these instruments are expected to provide an accurate characterization of key atmospheric and surface parameters to facilitate Fs retrieval for FLORIS. In thi…
Scientific simulations and optimization of the XGIS instrument on board THESEUS
2020
The XGIS (X and Gamma Imaging Spectrometer) is one of the three instruments onboard the THESEUS mission (ESA M5, currently in Phase-A). Thanks to its wide field of view and good imaging capabilities, it will efficiently detect and localize gamma-ray bursts and other transients in the 2-150 keV sky, and also provide spectroscopy up to 10 MeV. Its current design has been optimized by means of scientific simulations based on a Monte Carlo model of the instrument coupled to a state-of-the-art description of the populations of long and short GRBs extending to high redshifts. We describe the optimization process that led to the current design of the XGIS, based on two identical units with partial…
The New Generation of Resonant Laser Ionization Mass Spectrometers: Becoming Competitive for Selective Atomic Ultra-Trace Determination?
2002
A critical assessment of the present status of resonant laser ionization mass spectrometry (RIMS) as a specialized analytical technique for the field of atomic ultra-trace determination is attempted and a comparison with established mass spectrometric methods is made. Within the last years RIMS on atomic species has rapidly developed towards becoming a versatile experimental technique, in particular addressing those applications that require high selectivity in respect of isobaric or isotopic interferences. This progress is mainly based on the advent of easy-to-handle tunable solid-state laser systems for both pulsed and continuous operation, which are used in combination with modern compac…
Studies of CoxMg1-xO Solid Solutions Using Laboratory EXAFS-Spectrometer
1993
Studies of the local electronic structure and the short-range order in solid solutions Co x Mg1-x O with x equal from 0.02 to 1.00 have been carried out on the Co K-edge X-ray absorption spectra measured using the laboratory EXAFS-spectrometer. A non-monotonous change of the Co-O distance in the first coordination shell with the bent at x=0.5 has been established. The second coordination shell of cobalt has been formed by cobalt and magnesium atoms with a distribution close to statistical.
The Fluorescence Explorer (FLEX) Mission: From Spectral Measurements to High-Level Science Products
2021
The Fluorescence Explorer (FLEX) mission was selected in 2015, by the European Space Agency (ESA), as an Earth Explorer mission, with a launch planned for 2024. The key scientific objective of the mission is the quantitative global mapping of actual photosynthetic activity of terrestrial ecosystems, as a function of variable vegetation health status and environmental stress conditions. The measurements will have a spatial resolution of 300 m, adequate to resolve land surface processes associated to vegetation dynamics at a global scale. To be able to accomplish such objective, the FLEX mission carries the FLORIS spectrometer, specially optimized to map vegetation fluorescence with a spectra…