Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Spin-Orbit Interaction at Surfaces I
O 7.1: Vortrag
Montag, 22. März 2010, 11:15–11:30, H38
Spin filtering by Self-Assembled Organic Monolayers on gold — •Benjamin Göhler1, Volker Hamelbeck1, Matthias Kettner1, Georg F. Hanne1, Helmut Zacharias1, and Ron Naaman2 — 1Physikalisches Institut, Universität Münster — 2Department of Chemical Physics, The Weizmann Institute, Israel
Electron dichroism has been reported for vapours of chiral molecules [1]. Because of different interactions of spin-polarized electrons with chiral molecules the attenuation of polarized electron beams depends on the helicity of the electrons. Similarly the photoelectron yield of gold covered with organized organic thin films of chiral molecules shows a dependence on the circular polarization of the incident light, because the spin polarized photoelectrons of the gold substrate interact differently with the thin film [2]. In this presentation we show that these photoelectrons are in fact spin-polarized. Photoelectrons are emitted by 210 nm (5.9 eV) laser radiation which is sufficient to emit photoelectrons of the gold substrate but not to ionize the molecules of the organic layer. The self assembled layer of chiral molecules (ds-DNA) filters the electrons with a spin polarization of about 20%. The spin polarization is measured by a calibrated mini Mott analyzer.
[1] J.Phys.B. 30, 5491, 1997. [2] Science 283, 814, 1999.