Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1234515 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2009 | 5 Pages |
Abstract
According to the calculations the phenyl ring is twisted out of the benzopyrone plane by 28° in the electronic ground state whereas the nuclear frame is nearly planar in the lowest excited (nÏâ)1 (S1) state and is slightly V-shaped in the (ÏÏâ)3 (T1) and (ÏÏâ)1 (S2) states. The calculations clearly show that the T1 state has mainly ÏÏâ character. The large spin-orbit coupling of the S1 and T1 states and their small energy gap explain the high S1âT1 ISC rate for which a value of kISCâ3Ã1011 s is computed, in good agreement with experimental build-up times of the TnâT1 absorption. In the absence of collisions and other nonradiative processes, the T1 state of flavone is prediced to be long-lived with a pure phosphorescence lifetime of ÏPâ4 s, in qualitative agreement with low-temperature measurements. The much faster decay of triplet flavone observed in fluid solutions is ascribed to nonradiative processes.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Christel M. Marian,