Photoionization of the H atom in strong electric fields by resonant two-photon excitation

Journal Article · Sat Sep 01 04:00:00 EDT 1984 · AIP Conf. Proc.; (United States)

DOI:https://doi.org/10.1063/1.34668· OSTI ID:6388971

Welge, K H; Rottke, H

The photoionization of the H atom in strong electric fields, F, by resonant two-photon excitation, H(1)+VUV..-->..H(2)+UV..-->..H/sup +/+e, has been investigated at energies from the classical field ionization saddle point, E/sub s//sub p/ = 2 ..sqrt..F a.u., through the zero field ionization limit, E = 0, into the continuum, E>0. The atoms have been excited to single Stark levels in n = 2 with tunable pulsed VUV laser light around the Lyman-..cap alpha.. line in an atomic beam with sub-Doppler resolution. The ionization from selected Stark levels by the UV was observed as a function of the UV wavelength. The VUV and UV were linearly polarized either perpendicular, sigma, or parallel, ..pi.., to the electric field. Ionization spectra have been taken with (..pi..,..pi..), (..pi..,sigma), (sigma,..pi..), and (sigma,sigma) polarization and investigated at field strengths from 2-7 KV/cm. All spectra exhibit quasi-stable state structure superimposed on a continuum at energies 0>E>-Vertical BarE/sub s//sub p/Vertical Bar. For the first time, also oscillatory structures have been observed with the H atom, extending well into the continuum region, E>O, and below the zero field limit, E<0. Their field dependence follows proportionalF/sup 3/4/, with a deviation of a few percent. The oscillations appeared pronounced in (..pi..,..pi..) excited spectra, while not observable with the other polarization combinations.

• Research Organization: Fakultaet fur Physik, Universitaet Bielefeld, FRG
• OSTI ID: 6388971
• Journal Information: AIP Conf. Proc.; (United States), Journal Name: AIP Conf. Proc.; (United States) Vol. 119:1; ISSN APCPC
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular &amp; Chemical Physics-- Atomic &amp; Molecular Properties &amp; Theory
74 ATOMIC AND MOLECULAR PHYSICS
ATOMIC BEAMS
BEAMS
ELECTRIC FIELDS
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
HYDROGEN
INTERACTIONS
IONIZATION
LASER RADIATION
MULTI-PHOTON PROCESSES
NONMETALS
PHOTOIONIZATION
RADIATIONS
STARK EFFECT