ABSTRACT
The double ionization of xenon in the multiphoton regime has been studied at two wavelengths (0.77 and 0.79 microm) using an electron-ion coincidence technique and an intensity binned ion ratio method. Sharp resonant structures in the electron energy distribution correlated with the doubly charged ion, as well as a wavelength dependence of the Xe(2+)/Xe(+) ratio provides new insights. A mechanism involving the shelving of population in Rydberg states followed by excitation of a core electron is proposed.
ABSTRACT
The double ionization of argon and xenon in an intense laser field has been studied in detail using an electron-ion coincidence technique. The observed double ionization electron spectra in xenon show resonancelike structures here resolved for the first time. In argon, the featureless spectra are consistent with rescattering. This represents a clear transition in the dynamics of strong-field double ionization, analogous to the well-known transition between the tunneling and multiphoton regimes in single ionization.
ABSTRACT
The double ionization of helium in the strong-field limit has been studied using an electron-ion coincidence technique. The observed double ionization electron energy spectra differ significantly from the single ionization distributions. This gives new support to the rescattering model of double ionization and explicitly reveals the role of backward electron emission following the e-2e ionizing collision.
ABSTRACT
A ponderomotive-optical trap for energetic free electrons has been generated with a single, high-peak-power laser beam. The focal region consists of an intensity minimum at the center of the focus, with increasing intensities in all directions. The focus can be generated with a two-zone binary phase plate, or with a novel, coaxially segmented wave plate. This scheme can also be used to trap neutral atoms.
ABSTRACT
High-order harmonics have been generated by the use of an annular laser beam. The nonlinearity of harmonic production and the shorter wavelengths involved cause the harmonics to emerge strongly peaked on the laser axis. Thus the harmonics emerge from the focus inside the missing portion of the laser beam. This permits the laser to be blocked by an aperture that passes the harmonics.
