THE NATURE OF THE ABSORPTION BAND-SHAPE DENSITY EVOLUTION FOR THE 1STOVERTONE OF CO COMPRESSED BY N2

Infrared spectra of the 2 <-- 0 absorption band of CO, compressed by N 2 at various densities up to 220 amagat at about 296 and 187 K have be en analyzed. To interpret these spectra a line-by-line model has been applied, based on empirical corrections of the Lorentzian line-shape, which account roughly for the effects of line-mixing and the finite du ration of collisions. At room temperature, this model provides a satis factory agreement with experimental bandshapes, especially for the low er N2 densities. At low temperature, the calculated absorption differs significantly from that observed around the band center, with a discr epancy increasing with the N2 density. This difficulty is overcome by accounting for the binary-van der Waals complexes- CO ... N2 formation . The extent of these CO ... N2 complexes has been estimated from two models of bandshape fitting the experimental profiles and by a simple thermodynamic calculation.