Resonance Raman spectroscopy and theoretical study on the photodissociation dynamics of diuron in S2 state

Resonance Raman spectra (RRs) and quantum chemical calculations were used to investigate the photodissociation dynamics of diuron in S2 state. The RRs indicate that the photorelaxation dynamics for the S0???S2 excited state is predominantly along nine motions: the ring C?=?C stretch vibration ?12 (1593?cm-1), PhNH wag ?14 (1517?cm-1), CON(CH3)2 stretch ?23 (1365?cm-1), CCH wag in plane/ring C?=?C stretch ?24 (1297?cm-1), ring CH rock in plane/ring deformation ?27 (1233?cm-1), CCH wag in plane ?29 (1151?cm-1), PhCl (para) stretch ?35 (1028?cm-1), PhNH wag ?37 (913?cm-1) and ring breath ?44 (685?cm-1). Dissociation by PhCl (para) cleavage at S2 state directly or relaxation to T2 state by internal conversion (S2???S1) and intersystem crossing (S1/T2) is expected by similar to 250?nm irradiation based on the RRS, complete active space self-consistent field, configuration interaction singles and time-dependent density functional theory calculations. Copyright (c) 2012 John Wiley & Sons, Ltd.