Flash Photolytic Production, Reactive Lifetime, and Collisional Quenching ofO2lpar;b1Sgr;gplus;, ugr;prime;thinsp;equals;thinsp;0rpar;

摘要

Collisional quenching ofO2lpar;b1Sgr;gplus;, ugr;prime;thinsp;equals;thinsp;0rpar;at room temperature by O2and a variety of foreign gases has been investigated with a pulsed lifetime measurement technique.O2lpar;b1Sgr;gplus;, ugr;prime;thinsp;equals;thinsp;0rpar;has been produced in a pulsed mode through flash photolysis of O2in the vacuum uv and has been detected through the emission of the (0, 0) band at 7620 Aring; of the forbiddenO2lpar;b1Sgr;gplus;thinsp;rarr;thinsp;X3Sgr;gminus;transition. The (0, 0) band intensity has been measured as a function of time after the photolysis flash and as a function of the O2and foreign gas pressures. Quenching rate constants are derived from the reactive lifetimes. The photolytic production ofO2lpar;b1Sgr;gplus;, ugr;prime;thinsp;equals;thinsp;0rpar;from O2and the quenching by O2has been studied at O2pressures from 0.02ndash;100 torr. The observations at low O2pressures from 0.02 to about 1 torr are consistent with the previously established fastO2lpar;b1Sgr;gplus;rpar;production mechanism,O2thinsp;plus;thinsp;hngr;thinsp;rarr;thinsp;Olpar;1Drpar;thinsp;plus;thinsp;Olpar;3Prpar;,Olpar;1Drpar;thinsp;plus;thinsp;O2lpar;X3Sgr;gminus;rpar;thinsp;rarr;thinsp;Olpar;3Prpar;thinsp;plus;thinsp;O2lpar;b1Sgr;gplus;rpar;,in the Schumannndash;Runge continuum region. No emission of the (1, 1) and (2, 2) atmospheric bands has been observed indicating that under the conditions employed,O2lpar;b1Sgr;gplus;, ugr;prime;thinsp;thinsp;0rpar;is either initially formed only to a relatively small degree in this mechanism or thatO2lpar;b1Sgr;gplus;, ugr;prime;thinsp;thinsp;0rpar;is relaxed or quenched by O2within less than 103collisions. From the (0, 0) band fluorescence decay rates measured at O2pressures from 0.02 to about 0.5 torr a quenching rate constant of 4.5thinsp;times;thinsp;10minus;16cm3moleculeminus;1middot;secminus;1is derived. At higher pressures, the decay rate deviates from a linear dependence on the O2pressure indicating that the reactive lifetime is influenced by some secondary process at these pressures. The decay rate measured for example at 20 torr, O2would correspond to a quenching coefficient of 4.8times;10minus;17cm3moleculeminus;1middot;secminus;1. Quenching ofO2lpar;b1Sgr;gplus;, ugr;prime;thinsp;equals;thinsp;0rpar;by He, Ne, Ar, Kr, Xe, H2, N2, CO, CO2, SF6, NH3, H2O, CH4, C2H6, C2H4, NO, NO2, and N2O has been investigated by measuring reactive lifetimes at constant O2pressures as a function of the added foreign gas pressures. Quenching rate constants are reported and compared with previous results.