Berlin 2008 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 43: Phase Transitions IV

MM 43.4: Vortrag

Donnerstag, 28. Februar 2008, 16:45–17:00, H 0107

Photoinduced ultrafast volume changes in intermediate valence solids — •momar diakhate and martin garcia — Institut für Physik, Universität Kassel, D-34132 Kassel, Germany

We present a theoretical model for the description of the ultrafast structural response of intermediate valence solids to femtosecond laser excitation. Based on the promotional Ramirez-Falicov model we consider the femtosecond laser heating of $\gamma-$ Cerium and the subsequent ultrafast lattice expansion dynamics.

In particular we determine the thermodynamic and electronic properties of cerium metal at very high electronic temperatures (simulating the laser excitation). The possibility for a non-equilibrium photoinduced inverse volume collapse transition is discussed. The p-v-T equation of state is obtained from the Helmoltz free energy in the usual way of thermodynamic derivatives by considering an adiabatic expansion of the crystal at high temperature.

We take into account both the laser excited and the unexcited parts of the system, in oder to account for inertial confinement. The thermodynamic properties were obtained as function of time and used to calculate the shock velocity variation and in the surrounding (unheated) part of the sample.