Lowest-lying singlet and triplet states

FIGURE 23. Selected (U)B3LYP/6-311 - — -G(d,p) optimized bond lengths (A) of the phenolate anion in both lowest-lying singlet and triplet states... 

Jonas, V. Bohme, M. Frenking, G. Structures and energies of the lowest lying singlet and triplet states of C3H2 and C3F2. A theoretical-study. J. Phys. Chem. 1992, 96, 1640-1648. 

Experimentally, there is little to suggest that large anharmonicities may be expected for the low-lying electronic states of the aromatic and aza-aromatic molecules, at least on the evidence of the extensive sequence structure and the well-developed progressions observed for the lowest excited singlet and triplet states of many molecules. 

It is assumed that photochemical reactions originate from the lowest energy singlet and triplet excited states. They are due to absorption bands which have been described in Chapter 111 on the spectroscopy of nitro compounds the 7T — jr transition (ca. 210 nm) of high intensity and n —(ca. 270 nm) of a relatively low intensity some nitro compounds show the second transition n ca, 350 nm). It is accepted that the lowest lying singlet and triplet... 

Figure 5.31. Relative energies of the lowest singlet and triplet states of benzophenone and naphthalene, and triplet sensitization of naphthalene direct excitation of the higher-lying naphthalene S, state is prevented by a filter.

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