The H2O absorption lines broadened by air pressure were recorded using Bruker IFS 125 HR Fourier spectrometer in the 5900-6100 cm–1 spectral region. The intensities, broadening and shift coefficients of H2O absorption lines were retrieved for lineshape profile taking into account a dependence of the broadening on collision molecules speed. The atmospheric transmission was calculated with use of H2O line parameters from the HITRAN spectroscopic database and our data. A comparison with the atmospheric solar spectra measured using a ground-based Fourier spectrometer was carried out.
Air pressure induced broadening and shift coefficients for methane absorption lines in the 6000–6100 cm–1 region have been measured. The spectra were recorded using Bruker IFS 125 HR spectrometer at room temperature, at the spectral resolution of 0.01 and 0.007 cm–1 and in a wide pressure range of air. The multispectrum fittings with the quadratic speed dependent Voigt profile were performed to retrieve the broadening parameters for CH4 spectral lines. The atmospheric transmission of CH4 calculated by line-by-line method with use of absorption lines parameters from different spectroscopic databases and data obtained in this work was compared.
The results of calculations of the H2O continuum absorption coefficients for IR spectra in 1000-1300 cm-1 and 2000-2700 cm-1 regions and absorption coefficients in the wings of the CO2 bands in the IR spectrum are presented. It is shown that the calculation of the local line contribution to the total absorption should be related to the line shape so that the maximum boundary of local line contribution does not fall into the region of frequency detunings corresponding to the exponential decay. The tendencies to a change of the continuum absorption with variations in the local line contribution boundary remain the same in cases of using both the experimental coefficient and calculated according the asymptotic line wing theory as the total absorption coefficient.
The water vapor line broadening and shift coefficients of H2O absorption lines induced by hydrogen pressure were measured using a Bruker IFS 125HR spectrometer.
For the first time the absorption spectrum of 2 0 0 12 – 0 0 0 01 band of carbon dioxide, confined in nanoporous silica aerogel with the density of 0.009 g/cm3,was measured using a Bruker IFS 125 HR FTIR at room temperature and a spectral resolution of 0.008 cm-1. The obtained dependence of spectral line half-width values on rotational quantum numbers was studied and compared with data available in the literature.
The water vapor line broadening and shift coefficients in the ν1+ν2+ν3, 3ν2+ν3 and 2ν1+ν2 vibrational bands of H2O induced by hydrogen pressure were measured using a Bruker IFS 125HR spectrometer. These vibrational bands were investigated for the first time. The values of the broadening and shift coefficients were compared with the experimental data obtained for H2O–He and H2O–Ar optical systems
The silica modified by boehmite (15% of Al2O3 by mass) was produced by sol-gel method without supercritical drying processes. Aerogel SiO2/Al2O3 textural characteristics was studied by low-temperature nitrogen adsorption with annealing samples at the temperature range of 500−900°C. Concentration and the acidic centers force on the aerogels surface were determined by thermal desorption of ammonia. For the first time absorption spectra of ethylene confined in nanopores of SiO2/Al2O3 aerogels was recorded using a Bruker IFS 125 HR FTIR spectrometer in the 5500 – 6300 cm-1 region. The difference in profiles of adsorbed ethylene was shown.
The water vapor line broadening and shift coefficients in the ν1+ν2, ν2+ν3, ν1+ν3, 2ν3, 2ν1, 2ν2+ν3, and ν1+2ν2 vibrational bands induced by helium pressure were measured using a Bruker IFS 125HR spectrometer. The vibrational bands 2ν3 and ν1+2ν2 were investigated for the first time. The interaction potential used in the calculations of broadening and shift coefficients was chosen as the sum of pair potentials, which were modeled by the Lennard-Jones (6-12) potentials. The vibrational and rotational contributions to this potential were obtained by use of the intermolecular potential parameters and intramolecular parameters of H2O molecule. The calculated values of the broadening and shift coefficients were compared with the experimental data.
The absorption spectrum of 2 0 0 12 – 0 0 0 01 band of carbon dioxide, confined in 20 nm nanopores of silica aerogel, was measured with help of a Bruker IFS 125 HR Fourier transform spectrometer at room temperature and a spectral resolution of 0.01 cm-1. The obtained dependence of spectral line half-width values on rotational quantum numbers was studied and compared with data available in the literature.
The paper presents results of evaluation of size of aerogel pores, synthesized by the sol-gel method without the use of supercritical drying. The aerogel framework was formed by alumina nanosheets and silica spherical particles. Pore size distribution was bimodal with the maxima at 5.5 nm and 77 nm.
For the first time, the low-temperature (from -9 to 15 ° C) Fourier Transform Spectroscopy laboratory measurements of the pure water vapor absorption spectra are performed in the near-infrared spectral region, and self-continuum absorption is retrieved within 1600 cm-1 (6.25 μm) and 3600 cm-1 (2.7μm) absorption bands. The proportion of true-bound and quasi-bound water dimers in the equilibrium water vapor is derived by fitting their model spectra to the spectral features of the retrieved continuum. The results are in reasonable agreement with statistical calculations and support the idea of complimentary contribution stable and metastable dimers to the spectral structure of water vapor continuum within absorption bands.
The sulfur dioxide absorption cross sections, measured with a Fourier transform spectrometer at room temperature and varied pressure of SO2-N2 in the 260-330 μm region, are presented. The absorption spectra are obtained at a high spectral resolution of 0.5 cm-1. The measurements results are compared with SO2 cross section data from literature.
Measurements of the pressure shifts coefficients for H2O absorption lines have been performed in the 9403 - 9414 cm-1
spectral region with H2 , O2, Ar, Xe, Kr and air as foreign gases. The data on lines shifts coefficients have been obtained
from analysis of the H2O-H2, H2O-O2, H2O-Ar, H2O-Xe H2O-Kr and H2O-Air absorption spectrum recorded at room
temperature using Nd glass intracavity laser spectrometer with spectral resolution of 0.03 cm-1 and absorption sensitivity
of 10-8 cm-1. The pressure of H2O was varied from 10 Torr to 20 Torr and the pressure of the buffer gases - from 0 to
1000 mbar. The values of the line shifts coefficients for 8 lines have been derived from the recorded spectra, they ranged
from 0.009 cm-1/atm to 0.069 cm-1/atm. For each buffer gas a linear relationship of line shifts was measured.
Measurements and calculations of the oxygen pressure-induced shift coefficients for more than 100 water vapor absorption lines of the (000) - (011) and (000) - (110) bands have been performed. Experimental data on line shift coefficients were obtained from analysis of H2O - O2 room temperature absorption spectra at 11 different pressures of O2 over the range 148.5 Torr to 3800.4 Torr, using a Fourier transform spectrometer with spectral resolution of 0.0007 cm-1 and an optical pathlength of 84.05 m. Calculations of line shift coefficients were performed using the Anderson semiclassical impact theory.
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