Photoelectron spectroscopy of Rydberg states of atomic iodine

The photoelectron spectra obtained following two-photon resonant, three-photon ionization of atomic iodine via a number of Rydberg states are presented. Photoelectron spectra obtained via the (³{P}₂$)np${[1]}1/2$ levels and via the ${(}³P₀)4f[3]5/2 level demonstrate the production of state-selected I⁺ ³{P}₂$ and $³P₀ions, respectively, with ~85% efficiency. Photoelectron spectra obtained via the{(}³P₂)nf[3]5/2 levels show the effect of a perturbation by the (³{P}₀$)4f${[3]}5/2$ level, as both ${I}⁺$ ${}³P₂ and ³P₀ are observed. The relative magnitudes of the ³P₂ and ³P₀ photoelectron peaks are shown to be strongly dependent on the relative magnitudes of the (³{P}₂$)nf${[3]}5/2$ and ${(}³P₀)4f[3]5/2 photoionization matrix elements. Two additional processes are observed in the photoelectron spectra. These correspond to fluorescence of the resonant intermediate level to lower-lying levels, followed by ionization of those levels, and to energy transfer from I* ²{P}1/2$ atoms to Rydberg atoms, resulting in ionization of the latter.