Four-photon ionization dynamics of xenon

Three-photon resonance enhanced four-photon ionization of xenon at wavelengths between 313 and 371 nm has been investigated by means of a novel photoelectron imaging spectrometer [1]. Photoelectron images provide a direct view of the squared angular wave functions of the free electrons as well as their energy distribution. Preferential formation of Xe+ (2P1/2) is observed when intermediate ns [3/2] (J=1) states belonging to the 2P3/2 core series are excited in the three-photon step. The opposite behaviour is observed for the 7s' [1/2] (J=1) state. For the nd states the abundance of photoions in each fine structure state closely mirrors the core character of the three-photon intermediate