Itoh T. Photophysical processes in quinoxaline vapor at low pressure.
SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2003;
59:3019-3027. [PMID:
14583277 DOI:
10.1016/s1386-1425(03)00128-8]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Excitation and pressure dependence of fluorescence and phosphorescence quantum yields has been reinvestigated in detail for quinoxaline in the static vapor phase at pressure range from 10(-3) to 10(-1) Torr. It is shown that the ratio of the nonradiative rate from T(1)(pi, pi*) to the rate of the S(1)(n, pi*) approximately -->T(1)(pi, pi*) intersystem crossing decreases with increasing the excitation energy in the S(0)-->S(1) excitation region. The phosphorescence quantum yield measured as a function of the excitation energy at low pressure shows an abrupt decrease on going the excitation from S(0)-->S(1) to S(0)-->S(2), indicating the slow vibrational energy redistribution between the S(1) levels optically populated and those populated through the internal conversion from S(2) to S(1).
Collapse