Photophysical processes in quinoxaline vapor at low pressure.
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).
Itoh
Takao
T
Chemistry Department, Miyazaki Medical College, Miyazaki University, Kiyotake-cho, Miyazaki 889-1692, Japan. titoh@fc.miyazaki-med.ac.jp
D049449:Luminescence; D011789:Quantum Theory; D011810:Quinoxalines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D014835:Volatilization
D011810:Quinoxalines