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MO: Molekülphysik

MO 14: Ultrafast IR and Raman Probe and Control

MO 14.3: Talk

Monday, March 13, 2006, 17:00–17:15, H12

A picosecond thermometer and pressure gauge for H-bonded systems — •Marcus Schmeisser, Hristo Iglev, and Alfred Laubereau — Technische Universität München, Physik-Department E11, James-Franck-Straße, 85748 Garching

A spectroscopic method for sensitive temperature and pressure measurements in hydrogen-bonded materials on a picosecond timescale is demonstrated [1,2]. The method is verified for an isotopic mixture of ice at 200 K and ambient pressure using the OH- and OD-sretching vibrations for ultrafast heating of the sample. The same vibration modes are known to be sensitive probes for H-bonding and represent suitable tools to distinguish local ice or water components with a time resolution of a few picoseconds.

We calibrate our picosecond thermometer taking into account the isochoric character of the ultrafast temperature rise in the sample, i.e the simultaneous pressure increase because of the slow volume expansion (on the nanosecond timescale). We observe a temperature rise up to 20±2 K with a simultaneous pressure increase up to 26±4 MPa. Including the pressure-induced spectral changes in the data analysis we were able to extract the temporal evolution of the temperature and pressure changes in the sample. Our investigation shows that the use of a temperature scale is meaningful for ice as early as 25 ps after energy deposition [2].

[1] H. Iglev, M. Schmeisser, K. Simeonidis, A. Thaller und A. Laubereau, Nature (2006), in press.

[2] H. Iglev, M. Schmeisser, A. Thaller und A. Laubereau, subm.