Laser excitation of ${\mathrm{OH}}^{+}$ to rovibrational levels of the ${\mathrm{c}}^1$Π state results in predissociation to form ${\mathrm{O}}^{+}$+H and O+${\mathrm{H}}^{+}$. Rotational levels with parity ${\mathrm{-}\left(\mathrm{-}1\right)}^{\mathrm{J}}$ (f component) decay to form ${\mathrm{O}}^{+}$+H, whereas those of parity ${+\left(\mathrm{-}1\right)}^{\mathrm{J}}$ (e component) decay predominantly to form O+${\mathrm{H}}^{+}$. The branching is interpreted in terms of coupling of the c ${}_{}{}^1{}_{}{}^{}\mathrm{\Pi }$ state to nearby electronic states and dissociation continua. Signals are recorded by tunable dye laser irradiation of a fast mass-selected beam of ${\mathrm{OH}}^{+}$ and detection of ${\mathrm{O}}^{+}$ ions or neutral oxygen atoms.

• Received 19 July 1989

DOI:https://doi.org/10.1103/PhysRevLett.63.2216