Attosecond Science - Stirring Electrons
Dr Felix Frank
Imperial College, London, UK
2:30 pm Monday, 27 February 2012, EN102 Lecture Theatre (EN Building), Hawthorn.
In this talk I will present the attosecond (1as = 10-18 s) beamline of Imperial College, where we generate and characterise single attosecond pulses. The attosecond pulse is generated via high harmonic generation. Here, one of the shortest infrared laser pulses with a duration of less than two cycles is focused into an atomic gas such that the nonlinear interaction with the gas results in coherent radiation at XUV energies (~90 eV). The XUV pulse is measured by creating an electron replica of the optical pulse. These photoelectrons are then pushed around by the generating IR field, revealing the amplitude and phase of both pulses.
I will also talk about recent results, where we used orthogonally polarised 800 nm and 400 nm light fields to steer the electrons in the continuum in the high harmonic generation process. By changing the relative phase between the fields, we are able to control which electrons efficiently recombine with its parent ion and contribute to the high harmonic spectrum. Therefore, by stirring the electron in two dimensions, we can select long or short trajectory emission on a single-atom level.
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