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A: Fachverband Atomphysik

A 21: Interaction with Strong or Short Laser Pulses I

A 21.1: Hauptvortrag

Donnerstag, 11. März 2010, 14:00–14:30, F 107

Acceleration of neutral atoms in strong short pulse laser fields — •Ulli Eichmann — Max Born Institut, D-12489 Berlin, Germany

Kinematic effects on neutral atoms in focused moderate laser fields have been well studied in the past and have led, for example, to the development of optical dipole traps. Here we report on unexpectedly strong kinematic forces on neutral atoms in strong short laser pulses with intensities up to 10¹⁶Wcm⁻². We oberve accelerations with magnitudes as high as 10¹⁴ times Earth’s gravity, which result in measurable deflection of atoms despite the short laser pulse duration in the range of 40 to 120 femtoseconds. An explanation of our findings can be given in terms of the ponderomotive force acting on the quasi free photoelectron in the focussed laser field. Due to the Coulomb force the electron drags the ionic core until the laser pulse is over and the electron is left in a long lived bound excited state. Our measurements for different atomic species and different laser parameters are in very good agreement with predictions based on this model. Implications of our results for strong field physics and further prospects will be discussed.