Electron impact excitation of metastable states of benzene, toluene, and aniline

摘要

Electron impact excitation functions for the formation of metastable states of benzene, toluene, and aniline are measured under low pressure conditions (sim;1 times; 10minus;5torr) with an electron energy resolution of 0.3 eV. Considerable evidence is presented for assigning these metastables as the lowest triplet statesT1. Each excitation function exhibits several features at low electron energy (4ndash;15 eV), which are interpreted in terms of resonances which decay to giveT1and nonresonant exchange excitation processes. Comparison of these triplet excitation functions with the optical excitation functions for fluorescence (see the preceding paper) indicates that intersystem crossing does not make a major contribution toT1formation under the present experimental conditions. From timehyphen;ofhyphen;flight measurements a lower limit of 500 mgr;sec is estimated for the lifetime of the lowest triplet stateT1for these three molecules.