When solids are exposed to intense pulsed laser radiation, highly excited electronic states are created that are of both practical and theoretical interest. Time-resolved photoelectron spectroscopic methods developed in recent years provide an effective approach to this problem and have yielded considerable information, particularly on semiconductors. The experiment reported on here uses a short, strongly absorbed laser pulse to excite electrons to intermediate states. Then a probe pulse that may be coincident or delayed relative to the exciting pulse and may have the same or higher photon energy ejects electrons whose energy distribution is measured. This distribution can be related directly to the distribution in the intermediate states. We describe applications of the general technique to observe normally unoccupied states between the Fermi level and vacuum level, to measure dynamics of surface space charge layers and surface recombination, to measure hot-electron temperatures, and to determine the rates of electron energy relaxation processes. Results on Si(111) 7 x 7 and cleaved ZnTe(110) and CdTe(110) surfaces are described.
R. T. Williams,
J. P. Long,
M. N. Kabler,
"Photoelectron Spectroscopy Of Laser-Excited States In Semiconductors," Optical Engineering 28(10), 281085 (1 October 1989). https://doi.org/10.1117/12.7977092