Cm-seminar - TODAY - Reminder

[CM]

 JOINT ICTP/SISSA CONDENSED MATTER SEMINAR
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> Seminar Room - ICTP Leonardo Building  (first floor)
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> Wednesday, 27 May -     4:00 p.m.
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> Uwe BOVENSIEPEN   ( Freie Universität Berlin )
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> " Femtosecond time-resolved spectroscopy of  the solid state"
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> Abstract
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> Solids are characterized by their different degrees of freedom charge, 
> lattice, and spin. Coupling of these degrees of freedom to each other 
> results in fundamental phenomena like superconductivity 
> (electron-phonon coupling) or the Kondo effect (spin-dependent 
> electron scattering). Time-resolved spectroscopy employing femtosecond 
> laser pulses faciliates direct and independent access of these degrees 
> of freedom and occasionally novel insight into coupling mechanisms. In 
> this talk two examples will be presented. (a) Quasi-one dimensional 
> structurs form charge density waves. Using time- and angle-resolved 
> photoelectron spectroscopy we have succeeded to monitor the single and 
> many particle excitations in the charge density wave compound TbTe_3 
> close to thermodynamic equilibrium. In case of more intense optical 
> excitation non-equilibrium conditions are generated, which finally 
> lead to melting of the charge density wave and facilitate  an 
> identification of the responsible mode. (b) Electron injection from a 
> metal substrate into ice layers results in localization and subsequent 
> stabilization of these excess electrons, which occurs by 
> electron-induced rearrangement of water molecules. Due to the 
> permanent electrical dipole moment this process is refered to as 
> electron solvation and we find a pronounced correlation of ice 
> structure and solvation dynamics at such ice-metal interfaces. 
> Electron traps at crystalline ice surfaces, which exhibit extremely 
> long hot electron lifetimes up to minutes, present a model system for 
> specfic reaction sites as demonstrated for electron induced 
> dissociation of Freon adsorbed on ice.

-- 
Sandro Scandolo, ICTP | http://www.ictp.it/~scandolo



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Ms. M. Poropat
Secretary
Condensed Matter & Statistical Physics Section
The Abdus Salam International
  Centre for Theoretical Physics
Strada Costiera 11
34014 Trieste
Italy

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