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Resonance Raman spectra were obtained for benzamide in methanol and acetonitrile solutions with excitation wavelengths in resonance with the S3 state. These spectra indicate that the Franck–Condon region photodissociation dynamics have multidimensional character with the motions mainly along the benzene ring C==C stretch ν9, the Ph–CO–NH2 and ring benzene stretch ν14, the CCH in plane bend ν17, the Ph–CO–NH2 stretch and NH2 rock ν19, the ring trigonal bend ν23, and the ring deformation and Ph–CO–NH2 stretch ν29. A preliminary resonance Raman intensity analysis was done, and the results were compared to those previously reported for acetophenone to examine the substituent effect. Solvent effect on the short-time photodissociation dynamics of benzamide was also examined. A conical intersection point S2/S3 between S3 and S2 potential energy surfaces of benzamide was determined by using a complete active space self-consistent field theory computations. The structural differences and similarities between S3/S2 point and S0 were examined, and the results were used to correlate to the Franck–Condon photodissociation dynamics of benzamide in S3 state. [ABSTRACT FROM AUTHOR]

The resonance Raman spectra were obtained for both 2-thiopyridone (2TP) and its proton-transfer tautomer 2-mercaptopyridine (2MP) in water solution. Density functional theory (DFT) calculations were carried out to help elucidate their ultraviolet electronic transitions and vibrational assignments of the resonance Raman spectra associated with their B-band absorptions. The nanosecond time-resolved resonance Raman spectroscopic experiment was carried out to further confirm the assignment that the transient species was the ground state 2MP. The different short-time structural dynamics were examined for both 2TP and 2MP in terms of their resonance Raman intensity patterns. The transition barriers between 2TP and 2MP for S0, T1, and S1states are determined by using (U)B3LYP-TD and CASSCF level of theory computations, respectively. The excited state proton transfer (ESPT) reaction mechanism is proposed and briefly discussed. [ABSTRACT FROM AUTHOR]