Diode-laser measurements of N-2-broadening coefficients in the nu(7) band of C2H4

N-2-broadening coefficients have been measured for 35 lines of C2H4, in the v(7), fundamental transition, using a tunable diode-laser spectrometer. Th ese lines with 3 less than or equal to J" less than or equal to 23, 0 less than or equal to K-a(") less than or equal to 4, and 1 less than or equal t o K-i(") less than or equal to 22 are located in the spectral range 880-102 4 cm(-1). The collisional half-widths are obtained by modeling each spectra l line with a Voigt and a Rautian profile. The measured broadening coeffici ents belonging to transitions with the same J" generally increase with incr easing K-a(") and the coefficients decrease on the whole with increasing J" . These behaviors can be predicted by an approximate semiclassical calculat ion performed by approximating ethylene to a prolate symmetric-top molecule . (C) 2000 Academic Press.