RATE-CONSTANTS FOR REMOVAL OF METHYLENE (1B1) PREPARED IN THE (0,13,0), (0,14,0) AND (0,18,0) OVERTONES BY HELIUM AND SEVERAL HYDROCARBONS

Article abstract of DOI:10.1016/0584-8539(90)80176-Y

Methylene (¹B₁) was prepared by a two-step process: photodissociation of ketene at 308 nm (XeCl excimer laser) gave "cold" methylene ¹A₁ and CO .Subsequent excitation of the ¹A₁ electronic state using a dye laser produced the ¹B₁ state .Bending overtones v₂ = 13, 14 and 18 could be selected and their time resolved fluorescence studied in the presence of several gases.Very little dependence of overtone radiative lifetimes are found.Quenching rate constants are in all cases very fast, they range from 5*10^-11 cm³ molec^-1 s^-1 for quenching of overtone v₂ = 14 by helium to 1.1*10^-9 cm³ molec^-1 s^-1 for quenching of the same overtone by trans-2-butene.Chemical forces seem to be involved in the quenching by hydrocarbons.