PGI-1 Seminar: Prof. Eugene Krasovskii
ATTOSECOND STREAKING SPECTROSCOPY OF CRYSTAL SURFACES
- 30.Apr.2014 11:30
- PGI Lecture Hall
Basque Science Foundation, San Sebastian
The new generation of high intensity light sources has opened wide perspectives in solid state spectroscopy. In this talk, application of the laser streaking technique to the attosecond time-resolved photoelectron spectroscopy of solids will be discussed, with the focus on the theoretical description of the photoemission process.
In the laser-assisted photoemission, an ultra-short pulse of extreme ultraviolet radiation creates a photoelectron wave packet with a temporal spread within a fraction of the oscillation period of the laser light. The energy shift of the photoelectron spectrum caused by the acceleration by the laser field, as well as the distortion of the line shape, provide information about the temporal structure of the excitation process. This can be described by a phenomenological model based on a quasi-classical description of the interaction of the wave packet with the laser field.
In the talk, special emphasis is made on the role of the lattice scattering (band structure) of the outgoing electron in laser-assisted photoemission. In particular, in the vicinity of band gaps, the strong interaction with the crystal is shown to lead to a distortion and a temporal shift of the streaking spectrogram.
In the seminal experiment on tungsten a delay of approximately 100 attoseconds has been detected between the emission of photoelectrons from 4f and 5d states. This observation will be discussed in terms of conducting properties of the photoelectron finals states of the W(110) surface.
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