Abstract :
A variable-temperature single-pass absorption gas cell with an optical pathlength of 147.5 cm was designed and built for spectroscopic
measurements of gases of atmospheric interest. The cell is optically matched to a Bomem DA8.3 Fourier transform spectrometer. A
heating/cooling system enveloping the cell, used together with a Neslab ULT-80 thermal bath, allows spectroscopic studies of gas samples at
temperatures ranging from 205 to 350 K and at pressures up to 1 atm. Tests of the optical, thermal, and vacuum operation of the system were
performed. Spectra of the 3ˆ0 vibrational–rotational band of carbon monoxide were recorded from 225 to 348 K and used to determine the
rotational gas temperatures. These results were compared with values obtained using thermocouples, in order to assess the thermal
performance of the new system. A second temperature-controlled cell 25-cm long, able to withstand pressures up to 30 atm, was also used to
record CO spectra. We have recorded high-resolution FTIR spectra of CO and CO perturbed by N2 at temperatures from 295 to 348 K. The
spectra were analyzed to determine pressure broadening and pressure-induced shift coefficients, along with their temperature dependence for
several transitions in the second overtone band of CO. The results, especially for self-broadening, are in excellent agreement with other
recent measurements reported in the literature.
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