OBSERVATION OF A LASER-INDUCED STRUCTURE IN THE IONIZATION CONTINUUM OF SODIUM ATOMS USING PHOTOELECTRON ENERGY SPECTROSCOPY

We report an experimental analysis of a structure induced by a Nd:YAG laser embedding the sodium 5S(1/2) excited state in the ionization con tinuum. The induced structure is probed from the ground state via a on e-photon ionization. The experiment is performed on an atomic beam app aratus which uses a time-of-flight spectrometer for energy analysing t he emitted photoelectrons. The selectivity of this technique provides the best measurement of a laser-induced resonance in the photoionizati on spectrum reported to date. A good agreement is found between the th eory and experimental results.