A rapid decay channel of the lowest excited singlet state of 9-benzoyl-10-nitroanthracene generating 9-benzoyl-10-anthryloxy radical and nitrogen (II) oxide

In cyclohexane at room temperature, the lowest excited singlet state (1BNA∗ with a lifetime of 0.8 ps) of 9-benzoyl-10-nitroanthracene has a broad absorption band and its shift to shorter wavelengths with time can be ascribed to the wide wavelength-range superposition of an absorption band which increases and then decreases with time constants of 0.8 and 1.8 ps, respectively. Hence, this band is assigned to the absorption of a higher excited triplet state of 9-benzoyl-10-nitroanthracene or that of an intermediate (INT) shown later (or 9-benzoyl-10-nitrite) which is formed from 1BNA∗ and decomposes into 9-benzoyl-10-anthryloxy radical and nitrogen (II) oxide finally.