K. Fox

Measurements of argon-, helium-, hydrogen-, and nitrogen-broadened widths of methane lines near 9000 cm−1

Abstract Pressure-broadened widths of rotational-vibrational lines in CH 4 have been measured at very high spectral resolution in the R -branch of the 3 v 3 overtone. The broadening gases wer Ar, He, H 2 , and N 2 . Results are presented as averages for J -multiplets at ambient temperature. The overall values in cm −1 -atm −1 for these R -branch lines are 0.0651 (CH 4 -Ar), 0.0508 (CH[in4]-He), 0.0728 (Ch 4 -H 2 ), and 0.0715 (CH 4 -N 2 .

Symmetry-dependent broadening parameters for methane

Pressure‐broadened widths of vibration‐rotation lines in the infrared spectra of methane have been measured at very high resolution. Systematic variations of linewidths as a function of tetrahedral symmetry4 were found for a variety of foreign gases, and for both 12CH4 and 13CH4. These experimental results follow a pattern predicted in earlier calculations of scattering of argon from methane.

Spectral shifts of methane lines in collisions with hydrogen, helium, nitrogen, and argon

Abstract Pressure-induced shifts of rotational-vibrational lines in CH4 have been measured at very high spectral resolution in the R-branch of the 3v3 overtone. The colliding gases were H2, He, N2, and Ar. Results are presented as functions of rotational and tetrahedral quantum numbers. Mean values (in 10-3 cm-1 torr-1) for the R0-R6 multiplets are -0.01109 (CH4-H2), +0.00547 (opposite sense) (CH4-He), -0.01990 (CH4-N2), and -0.02162 (CH4-Ar).

Spectroscopic studies of methane in collisions with rare gas atoms and diatomic molecules

Abstract We have recently measured widths and shifts of IR rovibrational lines of methane in collisions with helium, argon, hydrogen, and nitrogen. We present a preliminary study of these data on the basis of polarizabilities of atoms and multipole moments of molecules. We compare these experimental and theoretical results, and make suggestions for further research.