Observation of electronic structure minima in high-harmonic generation.
We report detailed measurements of the high-harmonic spectra generated from argon atoms. The spectra exhibit a deep minimum that is shown to be independent of the laser intensity, and is thus a clear measure of the electronic structure of the atom. We show that exact field-free continuum wave functions reproduce the minimum, but plane wave and Coulomb wave functions do not. This remarkable observation suggests that electronic structure can be accurately determined in high-harmonic experiments despite the presence of the strong laser field. Our results clarify the relation between high-harmonic generation and photoelectron spectroscopy. The use of exact continuum functions also resolves the ambiguity associated with the choice of the dispersion relation.
Wörner
Hans Jakob
HJ
National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6.
Niikura
Hiromichi
H
Bertrand
Julien B
JB
Corkum
P B
PB
Villeneuve
D M
DM