The negative ion ${\mathrm{PtN}}^{\mathrm{-}}$ has been studied by autodetachment spectroscopy in a coaxial laser-ion beam spectrometer. Sharp resonances were observed at photon energies near the photodetachment threshold, and the sharp structure could be assigned as ${}_{}{}^1{}_{}{}^{}\mathrm{}_{}^1{}_{}{}^{}$Σ(v=0) transition, followed by autodetachment of the ${}_{}{}^1{}_{}{}^{}\mathrm{\Pi }$ state. A rotational assignment was accomplished and the observed linewidths as a function of rotational energy elucidate the dynamics of the autodetachment process. Saturation of this transition and the resulting optical pumping dips give a unique method of determining the absolute cross section of the transition.

• Received 15 January 1987

DOI:https://doi.org/10.1103/PhysRevA.36.699