title: Insights into mechanistic photochemistry of urea.
abstract: In this work, we have studied the mechanistic photochemistry of urea (NH(2)CONH(2)) by means of ab initio calculations on the stationary and intersection structures in the lowest three electronic states (S(1), T(1), and S(0)). Two dominant decay channels were found for NH(2)CONH(2) to decay from the S(1) state, internal conversion to the S(0) state via the S(1)/S(0) minimum-energy conical intersection, and intersystem crossing to the T(1) state in the vicinity of the S(1)/T(1) minimum-energy crossing point. Once in the S(0) state, the isomerization and deamination reactions prevail due to their low barrier heights. This is different from the mechanism proposed experimentally, in which the deamination and dehydration reactions proceed in the S(1) and T(1) states. The C-N bond cleavage was determined to occur mainly along the T(1) pathway as a result of the S(1)/T(1) intersystem crossing.
authors.affiliation: Chemistry College, Beijing Normal University, Beijing 100875, China.
authors.forename: Ganglong
authors.initials: G
authors.lastname: Cui
authors.forename: Lina
authors.initials: L
authors.lastname: Ding
authors.forename: Feng
authors.initials: F
authors.lastname: Feng
authors.forename: Yajun
authors.initials: Y
authors.lastname: Liu
authors.forename: Weihai
authors.initials: W
authors.lastname: Fang
mesh_terms: D003198:Computer Simulation; D055668:Photochemical Processes; D011789:Quantum Theory; D014508:Urea / Q000737:chemistry*
chemical_list: D014508:Urea