126 research outputs found
Quantum Theory of High Harmonic Generation via Above Threshold Ionization and Stimulated Recombination
Fully quantum treatment explicitly presents the high harmonic generation as a
three-stage process: above threshold ionization (ATI) is followed by the
continuum electron propagation in a laser field and subsequent stimulated
recombination back into the initial state. The contributions of all ATI
channels add up coherently. All three stages of the process are described by
simple, mostly analytical expressions. A very good quantitative agreement with
the previous calculations on the harmonic generation by H ion is
demonstrated, thus supplementing the conceptual significance of the theory with
its practical efficiency.Comment: Latex IOP stile, plus 1 figure in a PostScript fil
Multiphoton radiative recombination of electron assisted by laser field
In the presence of an intensive laser field the radiative recombination of
the continuum electron into an atomic bound state generally is accompanied by
absorption or emission of several laser quanta. The spectrum of emitted photons
represents an equidistant pattern with the spacing equal to the laser
frequency. The distribution of intensities in this spectrum is studied
employing the Keldysh-type approximation, i.e. neglecting interaction of the
impact electron with the atomic core in the initial continuum state. Within the
adiabatic approximation the scale of emitted photon frequencies is subdivided
into classically allowed and classically forbidden domains. The highest
intensities correspond to emission frequencies close to the edges of
classically allowed domain. The total cross section of electron recombination
summed over all emitted photon channels exhibits negligible dependence on the
laser field intensity.Comment: 14 pages, 5 figures (Figs.2-5 have "a" and "b" parts), Phys.Rev.A
accepted for publication. Fig.2b is presented correctl
Adiabatic Theory of Electron Detachment from Negative Ions in Two-Color Laser Field
Negative ion detachment in bichromatic laser field is considered within the
adiabatic theory. The latter represents a recent modification of the famous
Keldysh model for multiphoton ionization which makes it quantitatively
reliable. We calculate angular differential detachment rates, partial rates for
particular ATD (Above Threshold Detachment) channels and total detachment rates
for the Hydrogen ion in a bichromatic field with 1:3 frequency ratio and
various phase differences. Reliability of the present, extremely simple
approach is testified by comparison with much more elaborate earlier
calculations.Comment: 22 pages, 6 Postscript figure
- âŠ