Regensburg 2016 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 4: Dynamics in many-body systems: Equilibriation and localization
(Joint session of DY and TT organized by DY)

TT 4.11: Vortrag

Montag, 7. März 2016, 12:15–12:30, H47

Time evolution of the electron distribution function of thin copper films probed with broadband femtosecond optical pulses — •Manuel Obergfell and Jure Demsar — Universität Mainz

The time-resolved dynamics of the optical constants of thin copper films has been measured in the visible range. The photoinduced changes in reflectivity and transmission are based on the changes to the electron distribution function at the Fermi level. The dielectric function of copper is modelled at the d-band to Fermi level transition at photon energies up to 3 eV. With a low amount of sample dependent parameters the matching to the temperature dependence of the dielectric function of copper is achieved. Therefore we can reproduce standard thermomodulation. To extract the electron distribution function time dependently, the deconvolution is performed by matrix inversion. Our results demonstrate a highly non-thermal electronic distribution up to time delays of more than 1 ps depending on excitation density, at odds with the Two-Temperature model assumption. We extract the electron-phonon coupling constant from these data and compare the results to several recent theoretical models.