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Journal of Physics B Atomic Molecular and Optical Physics

Observation of a laser-induced structure in the ionization continuum of sodium atoms using photoelectron energy spectroscopy

R. Eramo, Stefano Cavalieri, Lorenzo Fini, M. Matera, Louis F. DiMauro

Published Sep 14, 1997• 29 citations
Publisher

Abstract

We report an experimental analysis of a structure induced by a Nd:YAG laser embedding the sodium excited state in the ionization continuum. The induced structure is probed from the ground state via a one-photon ionization. The experiment is performed on an atomic beam apparatus which uses a time-of-flight spectrometer for energy analysing the emitted photoelectrons. The selectivity of this technique provides the best measurement of a laser-induced resonance in the photoionization spectrum reported to date. A good agreement is found between the theory and experimental results.

DOI
10.1088/0953-4075/30/17/009

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We report the observation of a structure in the ionization spectrum of sodium, induced by a strong radiation field embedding the 5s 2^{2}2S1/2{\mathit{S}}_{1/2}S1/2​ state into the continuum. The structure, probed by single-photon ionization, shows a marked asymmetry, typical of a laser-induced continuum structure.
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Coherent control provides a quantum interference based method for controlling atomic and molecular dynamics. We report two experimental observations of different ways to achieve such a control in atomic photoionization continuum. One is the photoionization of sodium atoms, initially prepared in the 3P1/2 excited state, by a non resonant three-photon interaction with 1064-nm laser light and by a one-photon interaction with the third-harmonic field, at 355 nm. Interference between the two transition paths allows the control of the total ionization rate by varying the relative phase of the laser fields. The second experiment is the observation of the modification of the ionization continua of xenon through laser induced continuum structure (LICS). The multiphoton radiative decay of the xenon ground state into the two electronic continua, that correspond to the two fine structure levels of the ground state of the xenon ion, is varied by electromagnetically embedding a bound state of the atom into the two continua. Both experiments are performed on an atomic beam apparatus which uses a time-of-flight spectrometer for energy analyzing the emitted photoelectrons.
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