AN ANALYTICAL MODEL FOR COLLISIONAL EFFECTS ON SPECTRAL-LINE SHAPE FROM THE DOPPLER TO THE COLLISION REGIME

A spectral line shape model accounting for both the collisional confin ement narrowing of the Doppler distribution and the inhomogeneous effe cts due to the radiator speed dependence of the collisional broadening and shifting parameters is proposed. The velocity changes are assumed to be induced as well by hard as soft collisions. Doppler-collision c orrelations and speed-class exchanges are taken into account. A compar ison with the previous models used for the Doppler regime and for the collisional one is done. The present model also applies for the interm ediate regime where the two above mechanisms are simultaneously effici ent. The spectral line shape characteristics are exemplified through t he H-2-Ar and C2H2-Xe prototype molecular systems. (C) 1998 American I nstitute of Physics. [S0021-9606(98)01243-4].