Spin-forbidden radiative decay of the a /sup 4/Pi/sub u/ state of O/sup +//sub 2/
S.W. Bustamente, Mitchio Okumura, D. Gerlich, Hoi Sing Kwok, Lee R. Carlson, Y.T. Lee · OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 1987
The spin-forbidden radiative decay of a /sup 4/Pi/sub u/ O/sup +//sub 2/ has been measured in a radio frequency octopole ion trap. Photodissociation is used to probe the a /sup 2/Pi/sub u/ population as a function of trapping time. We have found that the a /sup 4/Pi/sub u/ state exhibits a multiple exponential decay, ranging from a few milliseconds to hundreds of milliseconds. The state dependence of the decay is seen in the photodissociation spectrum (b /sup 4/..sigma../sup -//sub g/reverse arrowa /sup 4/Pi/sub u/), which changes dramatically from 0.1 to 100 ms. The major changes in the spectrum are simulated by assuming that the F/sub 2/ and F/sub 3/ spin components of the a /sup 4/Pi/sub u/ state decay faster than the F/sub 1/ and F/sub 4/ components. We can account for this dependence on spin sublevel by assuming that the primary mechanism for radiative decay arises from spin-orbit coupling of the a /sup 4/Pi/sub u/ and A /sup 2/Pi/sub u/ states. Our results suggest that the a /sup 4/Pi/sub u/ radiative lifetime of 0.22 s measured by O'Keefe and McDonald reflects the decay of only the longest living a /sup 4/Pi/sub u/ sublevels.