Xiao-Min Tong

Probing molecular dynamics at attosecond resolution with femtosecond laser pulses

The kinetic energy distribution of D+ ions resulting from the interaction of a femtosecond laser pulse with D2 molecules is calculated based on the rescattering model. From analyzing the molecular dynamics, it is shown that the recollision time between the ionized electron and the D+2 ion can be read from the D+ kinetic energy peaks to attosecond accuracy. We further suggest that a more precise reading of the clock can be achieved by using shorter fs laser pulses (about 15 fs).

Friction Force for Charged Particles at Large Distances from Metal Surfaces

Abstract We present a theoretical study of the dissipative component of the force acting on a highly charged ion moving in front of a solid surface at large distances. The friction force (stopping power) of the surface is analyzed employing both the specular-reflection model and time-dependent density functional theory (TDDFT). Contributions from particle–hole and plasmon excitations are discussed. A simple method to include corrections due to the finite width of the plasmon resonance at large wavelength into the TDDFT description of stopping power is suggested.

Towards Attosecond Half-Cycle Pulses

We propose to tailor a burst of the harmonics generated by a bichromatic field interacting with helium to produce either a single half-cycle pulse or a train of attosecond unidirectional half-cycle pulses. Such a field will be an important tool to pump, control and probe electronic states near the ground state.

HOW TO READ A MOLECULAR CLOCK WITH SUB-FEMTOSECOND ACCURACY

We analyze the elementary processes leading to the double ionization of D2 molecules by a single femtosecond intense laser pulse. From the total kinetic energy release of the two D+ ions which exhibits distinct peaks depending on the laser intensity, pulse length and mean wavelength, we show that the double ionization of D2 by a short femtosecond laser pulse can serve as a molecular clock. We discuss how to read such a clock correctly and how to choose laser parameters so the clock can be read more accurately.