Photoemission using laser sources
| Head: |
Prof. Dr. Thomas Fauster |
| Assistants: |
Jinxiong Wang, Andrea Melzer, Daniel Kampa |
| Funding: |
Deutsche Forschungsgemeinschaft |
| Duration: |
1.4.2001 - 31.3.2005 |
| Aim: |
Time-resolved photoelectron spectroscopy using laser sources is to be used for the investigation of the electron dynamics at solid surfaces.
A multipass amplifier system with a repetition rate of 1 kHz produces pulses with an energy of 1.8 mJ, a pulse duration of 25 fs and a central wavelength of 800 nm. By focusing these laser pulses into a gas cell higher harmonics with energies >100 eV can be produced. Individual harmonics can be selected by a monochromator between the gas cell and the sample chamber. The energy of the emitted electrons is to be determined with a time of flight spectrometer.
With an optical parametric oscillator a second laser pulse can be produced, with a wavelength tunable from the infrared to the visible range.
Using this pulse for the primary excitation and the higher harmonics to emit the excited electrons the dynamics of electronic excitations at surfaces can be examined by varying the time delay of the two pulses.
To be examined are in particular the dynamics of the intra- and interband scattering processes at the surface states of Si(100). These fundamental information contributes to the understanding of semiconductor components, for which ballistic transport or surface recombination rates are important.
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