The propyl gallate is widely used as a triplet state
The increase in the energy gap between [S.sub.2] and [S.sub.1] due to solvent relaxation, observed for rubrofusarin, minimizes the influence of [S.sub.2] (n,[[pi].sup.*]) on [S.sub.1] ([pi],[[pi].sup.*]), favoring the population of [T.sub.1] for rubrofusarin (Figures 8C and D) due to the occurrence of favorable conditions for intersystem crossing between [S.sub.1] and [T.sub.3] and the significant increase in energy between [S.sub.1] and the adjacent triplet state
([DELTA]E([S.sub.1],[T.sub.3]) = 57.65 kJ [mol.sup.- 1]).
Furthermore, steady-state photo-induced absorption spectroscopy showed the presence of positive polarons at 1350 nm and triplet states
at 1100 nm (see Figure 2), the latter indicating triplet state
formation via charge transfer states .
While the formation of triplet state
(instead of singlet ones) is not desired in the typical applications of chemi-/bioluminescence, such states can have important roles in other applications.
The photosensitizer can be activated to singlet excited state by visible light absorption and then partial excited-state molecules convert into longer-lived triplet state
through intersystem crossing.
The singlet oxygen can be produced through the energy transfer process from the triplet state
of the photosensitizer to the triplet oxygen molecules .
Therefore, in the first step, the sulfur atom in triplet state
, [sup.3]S, excited to the singlet state, and the reaction can continue in the singlet state This is explained as follows.
The chromophore in an excited triplet state
is reduced either by an electron or by a hydrogen transfer from a compound in the environment.
Helium in this case is known as orthohelium (or triplet state
helium), emphasizing that its two electrons have spins with the same orientation.
After triplet state
excitation, benzophenone is able to abstract hydrogen from ether, amine, alcohol or thiol functional coinitiators, thus reactive centers can be generated on coinitiator molecules to initiate free radical polymerization.
Alternatively, the molecule may convert into an excited triplet state
(T) molecule via intersystem crossing that involves a change in the spin of an electron.