Femtosecond time-resolved photoelectron spectroscopy with a vacuum-ultraviolet photon source based on laser high-order harmonic generation

Journal Article · Wed Jun 15 00:00:00 EDT 2011 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3600901· OSTI ID:22062347

Wernet, Philippe; Gaudin, Jerome; Godehusen, Kai; Schwarzkopf, Olaf; Eberhardt, Wolfgang ^[1]

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1. Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin (Germany)

A laser-based tabletop approach to femtosecond time-resolved photoelectron spectroscopy with photons in the vacuum-ultraviolet (VUV) energy range is described. The femtosecond VUV pulses are produced by high-order harmonic generation (HHG) of an amplified femtosecond Ti:sapphire laser system. Two generations of the same setup and results from photoelectron spectroscopy in the gas phase are discussed. In both generations, a toroidal grating monochromator was used to select one harmonic in the photon energy range of 20-30 eV. The first generation of the setup was used to perform photoelectron spectroscopy in the gas phase to determine the bandwidth of the source. We find that our HHG source has a bandwidth of 140 {+-} 40 meV. The second and current generation is optimized for femtosecond pump-probe photoelectron spectroscopy with high flux and a small spot size at the sample of the femtosecond probe pulses. The VUV radiation is focused into the interaction region with a toroidal mirror to a spot smaller than 100 x 100 {mu}m{sup 2} and the flux amounts to 10{sup 10} photons/s at the sample at a repetition rate of 1 kHz. The duration of the monochromatized VUV pulses is determined to be 120 fs resulting in an overall pump-probe time resolution of 135 {+-} 5 fs. We show how this setup can be used to map the transient valence electronic structure in molecular dissociation.

• OSTI ID: 22062347
• Journal Information: Review of Scientific Instruments, Vol. 82, Issue 6; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
BEAM CURRENTS
DISSOCIATION
ELECTRONIC STRUCTURE
EV RANGE
FAR ULTRAVIOLET RADIATION
HARMONIC GENERATION
KHZ RANGE
LASERS
MEV RANGE
MIRRORS
MONOCHROMATORS
OPTICAL PUMPING
PHOTOELECTRON SPECTROSCOPY
PHOTONS
PULSES
SAPPHIRE
TIME RESOLUTION
VALENCE