Second singlet state

The enolic form has been found to be formed from the second singlet state in dilute solutions of biacetyl in water, methanol, and n-heptane.77 In aqueous solutions, the enol is stabilized and its quantum yield of formation is 0.10 0.02 and varies slightly with the wavelengths. 

Fluorescence has been seen from the second singlet state 111A, formed by absorption of light near 2800 A corresponding to the 0 -0 transition [Levine et al. (627), Oka et al (757)]. The quantum yield of lluorcsccncc is high (0.5 to 1) [Oka et al. (758)]. 

Photodissociation dynamics of this molecule were studied using the TOF technique to determine the velocity distribution of the fragments when the molecule is photolyzed with a KrF laser at 248 nm (182). Absorption at this wavelength leads to the excitation of the second singlet state, the B- -Ai state, from the X A ground state. From the TOF spectra of the CS fragment they were able to show that both of the following reactions occur ... 

The second singlet state and the first triplet state of the molecule belong to the configuration b b. . . with normal ... 

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