Observation of autoionization states by time-resolved optogalvanic spectroscopy

An effective method for the observation of the atomic autoionization states in a hollow cathode discharge is realized by laser optogalvanic spectroscopy. The temporal profile of the optogalvanic signal induced by three-color three-step photoionization is divided by two different components. One is a fast arising signal which corresponds to the pure photoionization, and the other is a slow signal induced by the conventional optogalvanic mechanism. By resolving the fast and slow signal in the temporal evolution, the autoionization signals are clearly extracted from the any other optogalvanic signal including bound-bound state transitions.