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Three different thermal transpiration models have been tested for a range of pressures and temperatures normally encountered in collisional cooling experiments. The calculated corrections for two of these models follow similar patterns and differ only in magnitude at a fixed sample temperature for sample pressures between 0 and 8 Torr. Corrections calculated from the third model follow a pattern similar to the other two models only at pressures above about two Torr. [ABSTRACT FROM AUTHOR]

We have constructed a stabilized low temperature infrared absorption cell cooled by an open cycle refrigerator, which can run with liquid nitrogen from 250 to 80 K or with liquid helium from 80 K to a few kelvin. Several CO infrared spectra were recorded at low temperature using a tunable diode laser spectrometer. These spectra were analyzed taking into account the detailed effects of collisions on the line profile when the pressure increases. We also recorded spectra at very low pressure to accurately model the diode laser emission. Spectra of the R(2) line in the fundamental band of 13CO cooled by collisions with helium buffer gas at 10.5 K and at pressures near 1 Torr have been recorded. The He-pressure broadening parameter (γ0=0.3 cm-1 atm-1) has been derived from the simultaneous analysis of four spectra at different pressures. [Copyright &y& Elsevier]

We studied the R(0) line profile in the CH4 ν4 band from room temperature to 188 K with N2 as a perturber, to 100 K with O2 as perturber, and from room temperature to 15 K using He as a perturber. The N2 and O2 measurements were performed over a total pressure range of 15–110 mbar, and for the He measurements the maximum sample pressure at 15 K was 1.10 mbar. Broadening parameters were determined, taking into account the confinement narrowing (Dicke effect), and narrowing parameters, deduced from the soft or hard collision model, are compared with the dynamic friction coefficient calculated values. We also obtained preliminary values for the temperature dependence of the N2, O2 and He line broadening parameters for this transition. [ABSTRACT FROM AUTHOR]