Diode-laser measurements and calculations of N2-broadening coefficients in the ν7 band of ethylene

N2-broadening coefficients have been measured for 41 lines of C2H4 at 173.2 K in the P, Q, and R branches of the ν7 fundamental band near 10 μm, using a tunable diode-laser spectrometer. These lines were individually fitted with a Voigt and a Rautian profile in order to determine their collisional widths. The resulting broadening coefficients, as well as those previously measured at room temperature for 35 transitions, are compared with values calculated on the basis of a semiclassical model of interacting linear molecules, using an atom-atom Lennard-Jones potential in addition to the electrostatic contributions. An overall satisfactory agreement is obtained for all the results at room and low temperatures. Finally the temperature dependence of the broadening coefficients has been determined through the temperature exponent n, experimentally for the 23 common transitions as well as theoretically for all the studied transitions.