Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 87: Symposium: Beyond Optical Wavelengths: Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation III (Invited Speakers: Christian Spielmann, Matias Bargheer, Philippe Wernet)

O 87.7: Vortrag

Freitag, 29. Februar 2008, 11:45–12:00, HE 101

Ultrafast Phase Transitions in Metastable Water Near Liquid Interfaces — •Bernd Abel — Institut fuer Physikalische Chemie, Universitaet Goettingen, Tammannstr. 6, 37077 Goettingen, Germany

Liquid-gas phase transitions in water are an everyday occurrence, however, phase transitions of metastable superheated water are hardly understood so far despite their importance in many technical processes. By using short laser pulses to deposit heat at a rate faster than the thermal expansion rate, it is possible to prepare extreme states of matter at temperatures well above the normal boiling point. Electron spectroscopy for chemical analysis (ESCA) is a powerful tool for the quantitative analysis of the composition and the chemical environment of molecular systems. Employing high harmonics soft X-ray (50 eV) and near infrared femtosecond pulses and liquid water microbeams in vacuum we were able to add the dimension of time to the liquid interface ESCA technique. Tracing time dependent chemical shifts, electron orbitals and *energies of valence electrons in liquid water in time, we have investigated the timescale and molecular signature of laser induced phase transitions of metastable water on a femto- and picosecond timescale. The time-resolved data have been compared and analyzed with quantum chemistry and molecular dynamics calculations.