Hydrogen and helium pressure broadening of CH3F between 1 K and 600 K

The hydrogen (Hz) and helium (He) pressure broadening cross sections have been measured between I and 600 K for the J = 2- 3, K = 0 and J = 1-2, K = 0 transitions of CH3F, respectively. This two and a half decade range in temperature makes possible the consideration of these collisions as a spectroscopic process in which the translational energy plays the role of the spectroscopic variable. For the collisions studied here the pressure broadening cross section is slowly varying in the semi-classical region above zz 100 K. but at lower temperature the cross sections change rapidly, with significant collision pair specific differences.