Resonance Raman spectroscopy and theoretical study on the photodissociation dynamics of diuron in S 2 state

Resonance Raman spectra (RRs) and quantum chemical calculations were used to investigate the photodissociation dynamics of diuron in S 2 state. The RRs indicate that the photorelaxation dynamics for the S 0  → S 2 excited state is predominantly along nine motions: the ring C = C stretch vibration ν 12 (1593 cm −1 ), Ph–N–H wag ν 14 (1517 cm −1 ), CO–N(CH 3 ) 2 stretch ν 23 (1365 cm −1 ) , CCH wag in plane/ring C = C stretch ν 24 (1297 cm −1 ) , ring CH rock in plane/ring deformation ν 27 (1233 cm −1 ), CCH wag in plane ν 29 (1151 cm −1 ), Ph–Cl (para) stretch ν 35 (1028 cm −1 ), Ph–N–H wag ν 37 (913 cm −1 ) and ring breath ν 44 (685 cm −1 ). Dissociation by Ph–Cl (para) cleavage at S 2 state directly or relaxation to T 2 state by internal conversion (S 2  → S 1 ) and intersystem crossing (S 1 /T 2 ) is expected by ~250 nm irradiation based on the RRS, complete active space self‐consistent field, configuration interaction singles and time‐dependent density functional theory calculations. Copyright © 2012 John Wiley & Sons, Ltd.