Measurements of nitrogen-, hydrogen- and helium-broadened widths of methane lines at 9030–9120 cm-1

Abstract Pressure-broadened widths of vibration-rotation lines of both 12 CH 4 and 13 CH 4 have been measured at very high spectral resolution in the R -branch of the 3ν 3 overtone. The broadening gases were N 2 , H 2 and He, as well as a mixture of H 2 and He. Results are presented as averages for J -multiplets at ambient temperature. The overall R -branch values for line widths in 12 CH 4 -N 2 , 12 CH 4 -H 2 , 12 CH 4 -He, 12 CH 4 -H 2 +He and 13 CH 4 -H 2 are 0.0711 ± 0.0064, 0.0687 ± 0.0030, 0.0429 ± 0.0012, 0.0545 ± 0.0030 and 0.0678 ± 0.0054 cm -1 atm -1 , respectively.