Three-photon near-threshold photoionization dynamics of isooctane.
The electron survival probability following three-photon (9.3 eV total) near-threshold photoionization of neat isooctane is measured with sub-50 fs time resolution. The measured dynamics are nonexponential in time and are well described by a diffusion-controlled electron-cation recombination model. Excitation-power-dependent studies indicate that the unperturbed three-photon threshold ionization is only observed for pump irradiance below 0.5 TW cm2. At excitation fields above this level, the signal is no longer cubic in the excitation irradiance, and the observed electron survival probability dramatically changes, decaying as a single exponential in time.
Healy
Andrew T
AT
Department of Chemistry, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55455, USA.
Underwood
David F
DF
Lipsky
Sanford
S
Blank
David A
DA