Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 53: Scanning Probe Methods II
O 53.4: Vortrag
Mittwoch, 13. März 2013, 16:45–17:00, H31
Voltage pulse shapes in time-resolved STM measured with photons — •Markus Etzkorn1, Christoph Große1, Klaus Kuhnke1, Sebastian Loth1, 2, and Klaus Kern1, 3 — 1Max-Planck-Institute for Solid State Research, 70569 Stuttgart, Germany — 2Center for Free-Electron Laser Science, 22761 Hamburg, Germany — 3École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Time-resolved STM measurements using electronic pulses enable the study of local dynamics in the ns-regime and below [1]. One necessary prerequisite for such measurements is the knowledge of the time-dependance of the transient bias voltage V(t) at the tunnel junction. Due to the high frequency limitations of the wiring and the impedance mismatches in the experiments, perfect pulses fed into the STM will deviate from perfectness when they reach the tunnel junction. Here we introduce a new concept that enables the direct measurement of the true transient bias voltage in the junction using the characteristic photon signal created by plasmon decay between tip and sample. It relies on the fact that both plasmon decay and photon detection are fast on the time scale of the variation of V(t). We proof that this method gives correct results by redundant measurements of the autocorrelation using an all-electronic pump-probe scheme. Over and above we show how this method can be used to characterize the transfer function of a given set-up, and how one can optimize the transient bias shape by chirp modulation of the applied pulses. [1] S. Loth, M. Etzkorn, C.P. Lutz, D.M. Eigler, A.J. Heinrich, Science 329, 1628 (2010).