Measurement of multiplet intensities and noble gas-broadened line widths in the V3-fundamental of methane

Integrated intensity data at 300°K for J-multiplets between P(11)and R(11) in the _{V3-fundamental of ¹²CH4} are presented, along with the intensity of the entire Q-branch, which also encompasses the Q-branch of the _{V3-fundamental of ¹³CH4}. These data, together with theoretical estimates for the intensities of J-multiplets of J > 11, sum up to a value of S_band= 284±14cm^?2atm^?1 at 300°K. This results is in excellent agreement with most of the previously published values for this parameter. Within experimental error, the intensities of the J-multiplets in the _{V3-fundamental do not seem to exhibit the strong anamolies that were characteristic of lines in the 2V3}-band.Line widths have been measured at 100°K, 130°K, 190°K, 250°K, and 300°K for R(0), R(1), and R(2) broadened by He, Ne and Ar. The temperature dependence of the line width is discussed for the three cases of broadening. In neon broadening at 300°K, the ‘effective mean line widths’ for multiplets R(3) through R(11) have also been obtained experimentally; their J-dependence is interpreted using Gordon's theory of line shapes in multiplet spectra.