【摘 要】
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The intrinsic reaction coordinate computations and ab initio molecular dynamic simulations at CASPT2//CASSCF/cc-PVDZ level of theory were used to deeply understand the photo-dissociation dynamics of O
【机 构】
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College of Chemistry Beijing Normal University Beijing 100875 China
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The intrinsic reaction coordinate computations and ab initio molecular dynamic simulations at CASPT2//CASSCF/cc-PVDZ level of theory were used to deeply understand the photo-dissociation dynamics of O3-H2O complex in highly(D)1A (1ππ*)excited state and its atmospheric implications.The ground state O3-H2O complex is promoted to populate in the highly excited SPP((D)1A ,1ππ*)state by~248 nm photo-excitation,which is mainly responsible for maximum absorption of ozone in stratosphere.This rapidly initiates the occurrence of the O-O bond fission in the SPP((D)1A ,1ππ*)state,producing the high energy of O(1D)within femtosecond timescale.The approaching of O(1D)and water molecule causes the broken of H-O bond in H2O to give rise to O2(a1Δg)+OH((X)2Π)+OH((A)2Σ)products along a downhill pathway.The excited state dynamic simulations conclude that the formation of hydroxyl radical is very sensitive to the spatial orientation between ozone and water molecules.The stable trans isomer is determined to possess a small portion in seven coexistent O3-H2O complex conformers,70%of which is the unique source to produce OH radicals in SPP((D)1A ,1ππ*)state.As a result,the quantum yield of atmospheric hydroxyl radical through the photolysis of the ozone-water complex is much lower than the previous expectation.
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