Predissociation dynamics of D-2 + hv -> D(1s(1/2)) + D(2p(1/2,3/2), 2s(1/2)) revealed by the spin-orbit state resolved fragment branching ratios and angular distributions

摘要

For molecular photodissociations, the spin-orbit state resolved fragment branching ratios and angular distributions provide deep insight into the dynamics. For the first excited state of the H(2p(1/2,3/2)) atom, a branching ratio measurement is a challenge because of small energy spacing between them. For the D(2p(1/2,3/2)) fragments from the predissociation of D2 + 14.76 eV D(1s) + D(2s, 2p1/2,3/2) in the 2p - C1 - u (n = 19) state, we made such measurements by pumping the D(2s, 2p(1/2,3/2)) fragments to high-lying Rydberg states that are subsequently ionized by a delayed-pulse electric field. In the 2p + C1 Pi(u) (nu = 19) state, the D2 molecule dissociates via both shape and Feshbach resonances correlating to the channels D(1s) + D(2p(3/2)) and D(1s) + D(2p(1/2)), respectively. The measured spin-orbit branching ratios, 2p(3/2)/(2p(1/2) + 2p(3/2)), correspond to the diabatic limit, 2/3, which indicates strong spin-orbit state mixings near the dissociation limits. The spin-orbit state resolved fragment angular distributions also support the diabatic dissociation mechanism and illustrate simultaneous shape and Feshbach resonances for the R(0) transition.