Measurements of collision-broadened line widths in the nu4-fundamental band of (C-12)H4 at low temperatures

Collision-broadened half-widths of several lines in the nu4 fundamental band of (C-12)H4 have been measured at low temperatures between 130 and 295 K using a tunable diode laser and the sweep integration technique. The broadening gases are H2, N2, He, and Ar. The temperature dependence of the measured line widths is described in terms of an exponent n, which is shown not only to be different for each broadening gas but also to depend upon the tetrahedral symmetry identification of the lines of CH4.