In conjunction with the University of Melbourne:

The Attosecond Heisenberg-Microscope

Max-Planck-Institut für Kernphysik, Heidelberg, Germany

11 am, Friday 28 January 2005, James Hardie Theatre, School of Architecture, University of Melbourne

Highly-charged ions at velocities close to the speed of light generate extremely strong (I = 10¹⁵ – 10²¹ W/cm²), ultra-short (t = 10^-19 - 10^-17 s) electromagnetic (half-cycle) pulses when passing target atoms, molecules or clusters at large impact parameters far outside the respective electron clouds. Depending on the strength of the field (proportional to q/v_p with q the charge state and v_p the velocity of the ion) and the magnitude of the momentum transfer in the collision, the interaction with the target can be interpreted in terms of the scattering of virtual photons (Compton scattering), the absorption of one (Bethe-Born approximation) or the simultaneous, incoherent absorption of "many" virtual photons (Weizsäcker-Williams method of equivalent photons). Kinematically complete experiments where the momenta of all emerging fragments are determined at various field strengths (q/v_p) provide the key to identify all of the above processes. The simultaneous emission of many electrons by "simultaneous" (within less than attoseconds) absorption of many virtual photons might open the unique possibility to "image" the correlated motion of electrons in ground states of atoms, molecules and clusters on a time-scale not accessible by any other method. In first experiments (GSI, Darmstadt), strong correlation between the emitted electrons in the continuum is found for double and triple ionization by means of intensity interferometry and using Dalitz-plots. Evidence is provided that the observed patterns are indeed due to the ground state correlation.

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