SPECTROSCOPY AND PREDISSOCIATION OF ${O_{2}^{+} \underline{f}^{4}\Pi_{g}}^{\ast}$
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Date
1982
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Ohio State University
Abstract
The transitions $\underline{f}^{4}\Pi_{g}(\upsilon-2, 3)leftarrow \underline{a}^{4}\Pi_{u} (\upsilon-5, 6)$ are observed at high resolution in $^{16, 16}O_{2}^{+},{^{16, 18}O_{2}}^{+}$, and $^{{18, 18}O_{2}}^{+}$ using ion photofragment spectroscopy. These vibrational levels of the $\underline{f}$ state are found to be quasibound by an intrinaic berrier in its rotationiess potential energy curve and to predissociate. Absorptions into the $\Omega = 5/2$ and $3/2$ substates produce a discrete spectrum from which the predissociation lifetimes of individual rotational levels can be determined. The $\Omega = 1/2$ and $-1/2$ substates, however, dissociate so rapidly that absorptions into them appear only as an underlying continuum in the band spectrum. A three-level optical-optical double resonance technique is used to isolate individual rotational levels in these substates, allowing their absorption linewidths to be explicitly measured. This technique further allows transitions into the nonpredissociated $\upsilon - 1$ levels of this state to be observed. The molecular constants and predissociation mechanisms of $\underline{f}^{4}\Pi_{g}$ will be discussed.
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$^{*}$ Research supported by AFOSR and NSF.