Photodissociation of N2O: Triplet states and triplet channel

TY - JOUR

T1 - Photodissociation of N2O: Triplet states and triplet channel

AU - Schinke, R.

AU - Schmidt, Johan Albrecht

AU - Johnson, Matthew Stanley

PY - 2011/11/21

Y1 - 2011/11/21

N2 - The role of triplet states in the UV photodissociation of N2O is investigated by means of quantum mechanical wave packet calculations. Global potential energy surfaces are calculated for the lowest two 3A ′ and the lowest two 3A′ ′ states at the multi-reference configuration interaction level of electronic structure theory using the augmented valence quadruple zeta atomic basis set. Because of extremely small transition dipole moments with the ground electronic state, excitation of the triplet states has only a marginal effect on the far red tail of the absorption cross section. The calculations do not show any hint of an increased absorption around 280nm as claimed by early experimental studies. The peak observed in several electron energy loss spectra at 5.4eV is unambiguously attributed to the lowest triplet state 1 3A′. Excitation of the 21A ′ state and subsequent transition to the repulsive branch of the 23A′′ state at intermediate NN-O separations, promoted by spin-orbit coupling, is identified as the main pathway to the N2(1g+)+O(3P) triplet channel. The yield, determined in two-state wave packet calculations employing calculated spin-orbit matrix elements, is 0.002 as compared to 0.005 0.002 measured by Nishida [J. Phys. Chem. A 108, 2451 (2004)]10.1021/jp037034o.

AB - The role of triplet states in the UV photodissociation of N2O is investigated by means of quantum mechanical wave packet calculations. Global potential energy surfaces are calculated for the lowest two 3A ′ and the lowest two 3A′ ′ states at the multi-reference configuration interaction level of electronic structure theory using the augmented valence quadruple zeta atomic basis set. Because of extremely small transition dipole moments with the ground electronic state, excitation of the triplet states has only a marginal effect on the far red tail of the absorption cross section. The calculations do not show any hint of an increased absorption around 280nm as claimed by early experimental studies. The peak observed in several electron energy loss spectra at 5.4eV is unambiguously attributed to the lowest triplet state 1 3A′. Excitation of the 21A ′ state and subsequent transition to the repulsive branch of the 23A′′ state at intermediate NN-O separations, promoted by spin-orbit coupling, is identified as the main pathway to the N2(1g+)+O(3P) triplet channel. The yield, determined in two-state wave packet calculations employing calculated spin-orbit matrix elements, is 0.002 as compared to 0.005 0.002 measured by Nishida [J. Phys. Chem. A 108, 2451 (2004)]10.1021/jp037034o.

M3 - Journal article

SN - 0021-9606

VL - 135

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

ER -