Hamburg 2009 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 32: Attosecond Physics III

A 32.3: Vortrag

Donnerstag, 5. März 2009, 17:30–17:45, VMP 6 HS-E

Strong field dynamics with electron wave packet replicas — •Paula Riviere, Olaf Uhden, Ulf Saalmann, and Jan-Michael Rost — MPI PKS, Dresden

We investigate theoretically the electron dynamics under a train of attosecond pulses (APT) and in the presence of a strong infrared (IR) laser field. Such a combined light field, where the phase of the APT with respect to the IR field can be controlled, has been experimentally realized [1]. Here, we are interested in the process where electron wave packet (EWP) replicas are created at a well defined phase in every cycle or half cycle of the IR field. Each EWP can then interfere with the others and, additionally, suffers a streaking due to the IR field. This process can be studied analytically.

As a function of the delay between APT and IR field we obtain the kinetic energy distribution of the electron as well as the ionization probability. We analyze their dependence on the number of replicas, the main attosecond pulse frequency and the IR field intensity, both for one or two attosecond pulses per IR period. The expression for the final wavepacket can be split into two factors: one that depends on the phase shift, and one that depends on the number of replicas. The ionization probability shows strong modulations as a function of the phase shift between APT and IR pulse for small mean energies of the continuum wave packets, while for higher energies the ionization probability does not depend on the shift, in line with the experimental observations for He and Ar, respectively [1].

[1] P. Johnsson et al., Phys. Rev. Lett. 99, 233001 (2007).