Femtosecond time- and angle-resolved photoemission spectroscopy

DIPC Seminars

Patrick Kirchmann, Fritz Haber Institute of the Max Planck Society Department of Physical Chemistry, Berlin
Donostia International Physics Center (DIPC).Paseo Manuel de Lardizabal, 4 (nearby the Facultad de Quimica), Donostia
Add to calendar
Subscribe to Newsletter
Femtosecond time- and angle-resolved photoemission spectroscopy In the last decade, femtosecond time-resolved methods have emerged as a powerful tool for the investigation of matter far from equilibrium. In my talk, I will focus on time- and angle-resolved photoemission spectroscopy (trARPES) and its application to solid state phenomena. trARPES allows investigating the population dynamics and energy relaxation in the occupied and occupied band structure directly in the time domain and in k-space; depending on the excitation conditions and samples, single-particle (quasi- particle lifetimes, scattering channels) can be addressed as well as cooperative phenomena (coherent phonons, collective modes, ‘phase transitions’) be induced. The simultaneous observation of the spectral function in energy space and its changes in the time domain allow qualitatively new insights and challenge our microscopic understanding on ultrafast time scales. Thus, trARPES might well become a new pivotal tool for material science questions. I will discuss a broad range of experimental examples such as the quasi- particle lifetimes in the 2D model system Pb/Si(111), which are governed by electron-electron processes and surprisingly well described by 3D Fermi-liquid theory [1]. Brand-new results on the topological insulator compound Bi2Se3 evidence that 50fs IR pulses are able to create a long-lived (>10ps) population in the spin-textured Dirac surface state due to scattering from bulk to surface bands [2]. The melting of the charge order in the quasi-2D compound TbTe3 highlights the cooperative nature of many-body phenomena [3]. My outlook will emphasize the importance of complementary diffraction studies using x-rays from Free Electron Lasers [4] and table-top femtosecond electron diffraction [5]. [1] P.S. Kirchmann et al. Nature Physics 6 (2010) 782 [2] J.A. Sobota et al. (submitted) [3] F. Schmitt et al. Science 321 (2008) 1649 [4] W.S. Lee, Y.D. Chuang at el. (submitted) [5] http://www.fhi-berlin.mpg.de/pc/sesd/SESD_research.html