Energy transfer from nitrogen chloride (a(1)Delta) to iodine atoms: A new chemical laser

Lasing of the I {dollar}rm(sp2Psb{lcub}1/2{rcub})to I (sp2Psb{lcub}3/2{rcub}){dollar} transition at 1.315 {dollar}mu{dollar}m has been produced by energy transfer from NCl (a{dollar}sp1Delta){dollar}. This was accomplished in experiments where the active species, NCl (a{dollar}sp1Delta){dollar} and I atoms, were produced by 193 nm photolysis of ClN{dollar}sb3{dollar} and CH{dollar}rmsb2Isb2{dollar} respectively. Comparision of the results with a kinetic model indicates that the inversion is pumped by NCl (a{dollar}sp1Delta){dollar} created in the chain decomposition of the ClN{dollar}sb3{dollar} remaining after the photolysis, rather than the NCl (a{dollar}sp1Delta){dollar} made in the initial photolysis. The kinetic model describing the system includes the energy transfer process, the aforementioned chain decomposition of the parent azide and various losses of the active species. The results of this model are in qualitative agreement with the observed chemiluminescent time profiles and the threshold times of the lasing events.; This demonstration began with the measurement of the rate constant of energy transfer between NCl (a{dollar}sp1Delta){dollar} and iodine atoms. This rate was measured by photolyzing mixtures of CH{dollar}rmsb2Isb2{dollar} and ClN{dollar}sb3{dollar} and observing the increase in the I ({dollar}rmsp2Psb{lcub}1/2{rcub}){dollar} at the 1.315 {dollar}mu{dollar}m. A steady state treatment that balanced the pumping and loss reactions showed the rate constant to be {dollar}rm(1.8pm0.3)times10sp{lcub}-11{rcub} cmsp3ssp{lcub}-1{rcub}.{dollar} Because of the large enhancements observed upon the additions of ClN{dollar}sb3{dollar} to the photolysis mixture, the yield to I ({dollar}rmsp2Psb{lcub}1/2{rcub}){dollar} was thought to be high. The quenching rate of I ({dollar}rmsp2Psb{lcub}1/2{rcub}){dollar} by ClN{dollar}sb3{dollar} was likewise measured and found to be {dollar}rm(2.0pm0.3)times10sp{lcub}-11{rcub} cmsp3ssp{lcub}-1{rcub}.{dollar}; The results of another experiment are reported; these being the rate constants for quenching of NCl (a{dollar}sp1Delta){dollar} by a number of diatomics thought likely to be encountered in a laser scale-up attempt. These rates are discussed in terms of crossing among potential energy surfaces of bound amine-like intermediates. Production of NCl (a{dollar}sp1Delta){dollar} from O{dollar}rmsb2 (asp1Delta){dollar} and ClN{dollar}sb3{dollar} was observed.; Lastly, the chain decomposition of ClN{dollar}sb3{dollar} is addressed. This phenomenon was observed during 249 nm photolyses of ClN{dollar}sb3{dollar} in which the 1.08 {dollar}mu{dollar}m emission of NCl a {dollar}to{dollar} X exhibits a time profile suggestive of chain decomposition of the parent azide. It is likely that the chain carrier is vibrationally excited N{dollar}sb2.{dollar}...