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 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+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
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 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.
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 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.
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.
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.
The grating spectrometer operating in near infrared and visible spectral regions with photoregistration system for the room and high temperature spectra investigations is presented. The spectrometer allows to investigate the absorption spectra with the spectral resolution of 0.036 cm-1 and the precition of the line position of 0.003 cm-1. Absorption spectra of the atmospheric air was recorded.
The investigations into the Intracavity laser spectroscopy of excited molecules in low temperature plasma performed at the Institute of Atmospheric Optics SB RAS are presented. Small size of the absorption layer allowed different ways of the molecule excitation: in electrical discharge, in plasma of laser spark. Investigation were performed using ICL-spectrometers in the visible and near IR regions with spectral resolution of 0.02 cm-1 and threshold absorption sensitivity of 10-8 cm-1 that corresponds to use 10000 m absorption path in classical spectrometry. The intracavity laser spectrometer with an additional channel for recording emission spectra is presented. The spectrometer is capable of recording weak absorption spectra of stable molecules and radicals in plasma with high threshold sensitivity, as well as monitoring the molecular composition of a gas using visible and UV emission spectra with temporal resolution of 25ns. Absorption spectra of CO2 and C2 were recorded in plasma. New vibration-rotation bands induced by transitions to highly excited states are assigned; spectroscopic constants of upper states were determined.
This work is devoted to the water vapor spectrum analysis in the near-IR region. The water vapor spectrum was studied using intracavity laser spectrometer in 8250-9100 cm-1 region with the spectral resolution of 0.05 cm-1 and at temperature of 1000 K. The spectra identification was done. More than 10 vibrational bands were recorded and analyzed.
The main purpose of this study is to report measurements of H216O line positions at the temperature of 1300 K in 1.06 micrometers region. The H2O frequency measurements were used to obtain values of rotational energy levels for the (111) and (012) vibrational states for J < 18.
The water vapor absorption spectra between 11,600 and 12,750 cm-1 have been recorded with the Fourier-transform spectrometer (Kitt-Peak, Az) at the resolution of 0.012 cm-1 and with the path length of 434 m. Three spectra were used for the analysis: two spectra of water vapor recorded with the Kitt Peak interferometer at the pressure of 1.5 and 17 Torr and the spectrum published by Toth. The experimental details and data reduction procedure have already been discussed, the line assignments were performed simultaneously with calculation of the line positions and intensities that allowed one to obtain an accurate set of experimental rotational energy levels for the eight interacting vibrational states. (131), (211), (013), (230), (112), (032), (051) and (310).
The H218O spectrum has been recently investigated between 11,300 - 13,600 cm-1 covering the 3v plus (delta) spectral region where v is the quantum of the stretching vibration and (delta) is the quantum of the bending vibration. We present here the study of the 4v and 4v plus (delta) region between 13,000 and 15,500 cm-1. Spectra of 18O enriched water vapor have been recorded by means of Fourier-transform spectroscopy. The experimental details have been discussed. The experimental conditions are given.
High resolution intracavity laser spectrometers were developed in 8000 - 11000 cm-1 spectral region. Threshold sensitivity of the spectrometers (10-7 - 10-8 cm-1) allows one to carry out effective investigation of high vibrational-rotational water vapor states at low and high temperatures. Vibrational states of H216O, H218O, D2O and HDO were investigated in a spectral region up to 11000 cm-1. Spectroscopic parameters were determined and vibrational parameters were used for calculation of the vibrational energy levels up to 16000 cm-1. New types of resonances between states of different polyads have been found.
Investigation of an absorption spectrum of D-isotope species of water vapor (one of the main absorption components of the atmosphere) in the two regions: 9161 - 9300 cm-1 and 10280 - 10770 cm-1 was carried out using a F2+:LiF color center and a Nd3+ glass intracavity laser (ICL) spectrometers with threshold sensitivity to absorption about 10-8 cm-1.