Dissociation lifetimes and level mixing in overtonehyphen;excited HN3(Xtilde;thinsp;1Arsquo;)

摘要

Vibrational overtone photodissociation is used to examine the spectroscopy and vibrational predissociation lifetimes of HN3in its ground electronic state. Direct overtone pumping of the Nndash;H stretching levels 5ngr;NHand 6ngr;NHprepares molecules in selected states (v,J,K) near 15thinsp;100 and 17thinsp;700 cmminus;1of vibrational energy; spinhyphen;forbidden NH(Xthinsp;3Sgr;minus;) dissociation fragments are detected by laserhyphen;induced fluorescence. Photodissociation spectra of beamhyphen;cooled HN3display mixing of individual rotational levels of thenngr;NHvibrations with several background states, with derived coupling matrix elements in the range 0.01ndash;0.1 cmminus;1. Vibrational predissociation lifetimes of mixed components of 5ngr;NHare state specific, with variations of a factor of 2 for only 0.1 cmminus;1energy differences. Average lifetimes for lowJ,Kare 210 ns for 5ngr;NHand 0.95 ns for 6ngr;NH. The ratio of decay rates for the two overtone levels,k(6ngr;NH)/k(5ngr;NH)=220, is much greater than predicted by statistical theory, which gives a ratio of 4.