In:
The Journal of Chemical Physics, AIP Publishing, Vol. 70, No. 10 ( 1979-05-15), p. 4496-4508
Abstract:
A laser-excited fluorescence method has been used to determine the rates at which CF2HCl molecules dissociate into CF2+HCl fragments during CO2 laser pulses of uniform fluence and known intensity. A study has been made of the dependence of the rate on CO2 laser intensity and pressure of Ar buffer gas from the collision-free regime to atmospheric pressure. The effect of increasing Ar pressure is initially to increase the CF2HCl dissociation rate; above a moderate pressure (∼50 Torr), the rate is independent of Ar pressure up to atmospheric pressure. The data has been compared to a model, which adequately reproduces all the experimental data. The model treats the effect of collision between CF2HCl and the argon buffer gas in terms of rotational equilibration or ’’hole filling’’ in the discrete energy level region of CF2HCl. The discrete energy levels are interfaced to a quasicontinuum of vibrational–rotational states in a self-consistent manner which incorporates a background of nonpumpable CF2HCl states as a finite heat bath interacting with the pump mode. The model is used to calculate the rate of formation of product CF2 molecules as a function of argon pressure and CO2 laser intensity. The quasicontinuum for CF2HCl is predicted to begin about four quanta above the ground state. The absorption cross section in the quasicontinuum is shown to decrease from 10−18 to 10−20 cm2 at V=15. The energy distribution in CF2HCl is predicted to be decidedly nonthermal both below and beyond threshold.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
1979
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
