Diode-laser measurements of N2-broadening coefficients in the ν7 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. These 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 to K-i(") less than or equal to 22 are located in the spectral range 880-1024 cm(-1). The collisional half-widths are obtained by modeling each spectral line with a Voigt and a Rautian profile. The measured broadening coefficients belonging to transitions with the same J" generally increase with increasing K-a(") and the coefficients decrease on the whole with increasing J". These behaviors can be predicted by an approximate semiclassical calculation performed by approximating ethylene to a prolate symmetric-top molecule. (C) 2000 Academic Press.