Penning ionization spectroscopy using the optogalvanic effect

The optogalvanic effect is proposed and demonstrated as a new technique for quasiresonant Penning ionization spectroscopy in a discharge plasma of mixtures of rare gases and metal vapors. A calcium and neon mixture is used as a prototype. Neon's lowest metastable level, ³P₂ at 134 034 cm^-1, is within kT from the excited state of ²D _3/2,5/2 of Ca⁺. Thus Penning ionization occurs to an excited state of the ion. This process strongly alters the optogalvanic signal and has its own signature. In fact, other energy transfer processes should also change the time dependence of the optogalvanic signal.