Excited states dynamics with x-rays /UE56_1-PGM

The instrument FEMTOSPEX Surface Dynamics is part of FemtoSpeX which allows to perform angle- and time-resolved photoelectron spectroscopy using the slicing facility. The acceptance angle of the spectrometer is max. 60 °. The time resolution is given by the pulse length of the X-ray pulses from BESSY II. One can also do picosecond measurements using the high resolution (1200l/mm) grating. An ultrafast laser system with OPA (optical parametric amplifier) allows for excitation of the sample at various wavelengths.

The pump laser system can run at up to 6kHz with about 1.2mJ per pulse (800nm) but can also be used at reduced repetition rates of 3kHz and 1.5kHz. The system delivers 800nm laser pulses of about 100fs length with a power of up to ~10W. For 800nm and the 2nd harmonic, i.e. 400nm, variabel attentuation and polarisation are available. For the tunable wavlengths created by the OPA we can currently only offer fixed attenuations by using ND filters.

Selected Applications:

• Core-hole-clock (CHC) Spectroscopy
• time-resolved Photo Electron Spectroscopy
• Photo Electron Diffraction

Sliced and unsliced raw data of Au 4f lines. a) Slicing off b) slicing on c) Difference of a) and b)

Methods

EXAFS, NEXAFS, Time-resolved absorption, ARPES, XPS, XPD, Time-resolved PES

Remote access

not possible

Time resolved electronspectroscopy on solid surfaces with femtosecond and picosecond laser-pump/X-ray-probe ArTOF spectroscopy and method development.