Seminars Archive

Mechanisms of high-order photoemission from metal surfaces

Abstract
We report on recent experiments addressing high-order photoelectric effects from the Cu(001) surface, investigated by interferometric time-resolved multiphoton photoemission induced by ultrashort laser pulses. We discuss the coupling induced by multi-photon-absorption phenomena between various electronic states of the surface. We show the appearance of resonant and nonresonant above threshold photoemission (ATP) effects and discuss the information they can provide concerning the photoemission process in itself [1]. We exploit the light-induced coupling between the copper bulk d-bands and the Cu(001) surface states to induce a net spin polarization in the Cu(001) image potential states [2], and demonstrate the possibility of tuning such a spin polarization by interferometric control of the exciting laser pulses [3]. Finally we discuss the possibility of directly observing a competition effect between optical harmonic generation and high-order photoemission at metal surfaces by simultaneously monitoring the optical and photoelectric response of the material as a function of a varying sample workfunction. [1] F. Bisio, M. Nyvlt, J. Franta, H. Petek, J. Kirschner “Mechanisms of high-order perturbative photoemission from Cu(001)‿ Physical Review Letters 96, 087601 (2006). [2] A. Winkelmann, F. Bisio, R. Ocaña, W. –C. Lin, M. Nyvlt, H. Petek and J. Kirschner ‿Ultrafast optical spin injection into image-potential states of Cu(001)‿ Physical Review Letters 98 (2007) 226601. [3] A. Winkelmann, W. -C. Lin, F. Bisio, H. Petek and J. Kirschner \"Interferometric control of spin-polarized electron populations at a metal surface observed by multi-photon photoemission\" Physical Review Letters 100 (2008) 206601