Dynamics of electronic wave packets in field emission and intense-field laser-atom physics

High-order harmonic generation in a tightly focused laser beam

The force due to the transverse magnetic field of a laser beam drives an electron in the direction of laser propagation, thereby impeding the recollision mechanism for high-order harmonic generation. The longitudinal electric field component of a tightly focused Gaussian beam can sufficiently counteract the magnetic force to enhance the harmonic yield substantially. For tight focusing and a laser intensity of 10(18) W/cm2, it can raise the harmonic yield by several orders of magnitude.

Imaging molecular structures by electron diffraction using an intense few-cycle pulse

As an intense few-cycle pulse interacts with an atomic or molecular target, its strong oscillating field may first pull electrons out of the target and subsequently drive them back to scatter on the target. The scattering may occur only a few times or even once during the interaction. This unique property of few-cycle pulses enables one to image ultrafast transient structures of matter by the means of pulse-driven electron diffraction. We demonstrated this phenomenon with K(+)(2) via three-dimensional calculations of the time-dependent Schro dinger equation.

Rescattering processes for elliptical polarization: A quantum trajectory analysis

High-harmonic generation and high-order above-threshold ionization spectra calculated in the strong-field approximation are analyzed in terms of the complex space-time orbits that result from a saddle point analysis of the underlying integrals. For elliptical polarization, the plateaus of the spectra of high-harmonic generation and high-order above-threshold ionization each turn into a staircase of very similar appearance. Each step of the stair can be traced to a particular pair of orbits which are almost identical in both cases.