Shift from an inverse to a normal isotope effect on the non-radiative decay rate of anthracene-d(10) observed under partially jet-cooled conditions

摘要

The absorption and fluorescence excitation spectra of anthracene-d(10) in the first excited singlet state were measured under partially jet-cooled conditions. From the ratio of the corresponding peak intensities of both spectra the fluorescence quantum yields were evaluated for a few sequence bands as well as single vibronic levels. In contrast to the case of anthracene-h(10), the values for the sequence bands (Phi(f) = 0.17-0.24) exceed that of the 0(0)(0) band (Phi(f) = 0.13), suggesting a resume of normal isotope effect on intersystem crossing. This novel finding is discussed in relation to the fluorescence Lifetimes of anthracene-d(10) measured in the gas phase. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 24]