TB3 - Measurement of vibrational-vibrational exchange of highly excited states of diatomic molecules where the collisional probability is approaching unity

An experimental method, employing a fast population perturbation technique, is described to measure the vibrational-vibrational (
VV
) collisional probability
P\min{r,r-1}\max{\upsilon,\upsilon+1}
of a diatomic molecule for large vibrational quantum numbers
r
and υ. The relaxation of the perturbed gain of a pair of vibrational levels is a function of the vibrational populations and
VV
rate constants
K\min{\upsilon,\upsilon+1}\max{r,r,-1}
. The numerical inversion of the
VV
master rate equations determining this relaxation does not give unique value for
K\min{r,r-1}\max{\upsilon,\upsilon+1}
(or
P\min{r,r-1}\max{\upsilon,\upsilon+1}
), but lower bounds can be evaluated and with empirical formulas, having several adjustable constants, it can be shown that probabilities of the order of unity are required to satisfy the experimental data. The method has been specifically applied to the CO molecule, but other molecules such as HX(X = F, C1, Br), NO, etc., could also be measured.