Electron-hydrogen collisions with dressed target and Volkov projectile states in a laser field. (Reannouncement with new availability information)

Technical Report · Thu Dec 31 04:00:00 EST 1992

OSTI ID:166856

Smith, P H; Flannery, M R

Cross sections for the 1S-2S and 1S-2P0 transitions in laser-assisted, e- -H(1S) collisions are calculated in both the multichannel eikonal treatment and the Born wave approximation, as a function of impact energy and laser field intensity. The laser considered is a monotonic, plane-polarized CO2 laser (photon energy = 0.117 eV) with the polarization direction parallel to the initial projectile velocity. The first part of this paper confines the laser perturbation to the bound electrons of the atom. A semiclassical Floquet approach is used to dress the hydrogen atom in this soft-photon weak-field regime, and is shown to reveal a concise description of the laser-assisted collision. The Floquet dressing is compared to dressing by the traditional time-dependent perturbation theory, showing that the perturbative approach gives an incomplete description of the laser interaction, and cannot predict the distinct features provided by the Floquet approach. The second part of the paper extends the laser perturbation to the projectile electron, and the familiar Volkov dressed states are used. Although in the range of impact energies and electric field strengths considered, the Volkov dressed states exert significant influence on the cross sections for individual state-to-state transitions, which involves absorption or emission of a given number of photons, they have only a negligible effect on the cross sections when summed over all absorptions and emissions. Special attention is given to synchronizing the time frame of the laser field with the time frame of the trajectory of the collisional species orbit. This requires the inclusion of a phase shift within the vector potential of the laser field.

• Research Organization: Georgia Inst. of Tech., Atlanta, GA (United States). School of Physics
• OSTI ID: 166856
• Report Number(s): AD-A--250432/2/XAB; GIT--89-009; CNN: Grant AFOSR-89-0426
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ABSORPTION
BORN APPROXIMATION
CROSS SECTIONS
ELECTRON-ATOM COLLISIONS
FLOQUET FUNCTION
HYDROGEN
LASER RADIATION
PERTURBATION THEORY
PHOTONS
POLARIZATION