Collisional relaxation in SF6 gas and its mixtures with He and Xe is studie
d by photon echo and stimulated photon echo methods from the standpoint of
the possibility of identifying the contributions of different types of coll
isions. The nonexponential nature of the kinetic curve of the photon echo i
s clearly observed for pure SF6, it is weaker in the mixture SF6+Xe, and it
is virtually completely absent for high degrees of dilution of SF6 with he
lium. These features can be explained on the basis of estimates, made from
experimental data, of the critical delay between the exciting pulses (for w
hich the nonexponential behavior should be most strongly manifested). In pu
re SF6 it is possible to distinguish the contribution of the inelastic chan
nel (rotational relaxation) and the contribution of weak collisions. To dis
tinguish successfully the relaxation channels in mixtures with buffer gases
a heavier buffer gas and a much better time resolution must be used. It is
shown that data obtained on the orientation and alignment relaxation rates
by the stimulated photon echo method can serve as an upper limit for the r
ates of inelastic processes which cannot be measured by the photon echo met
hod. The combined use of photon echo and stimulated photon echo methods mad
e it possible to obtain data on the cross sections for elastic and inelasti
c scattering of the collisional pairs SF6-SF6, SF6-Xe, and SF6-He. (C) 1999
American Institute of Physics. [S1063-7761(99)00507-7].