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O: Fachverband Oberflächenphysik
O 99: Organic Molecules on Inorganic Substrates VI: Adsorption, Growth and Networks
O 99.2: Vortrag
Donnerstag, 19. März 2020, 10:45–11:00, GER 38
Electron transmission through alpha-helical polyalanine investigated by STM and STS — •Nguyen Thi Ngoc Ha1, Diana Slawig2, Yossi Paltie3, and Christoph Tegenkamp1,2 — 1TU Chemnitz, Germany — 2Leibniz University, Hannover, Germany — 3Department of Applied Physics, Hebrew University of Jerusalem, Israel
Alpha-helical molecules recently have attracted much attention in view of electron propagation along the helical backbone structure which comes along with an efficient spin polarization [1]. In this study, we investigated the growth and electronic levels of molecular mono- layer structures of helical polyalanine-based peptides (PA) on Au(111) and HOPG surfaces by scanning tunneling microscopy (STM), spec- troscopy (STS) under ambient conditions. The self-assembled mono- layer (SAM) films revealed a high degree of lateral and rotational order [2]. Due to formation of Au-S bonds on Au(111), resulting from the termination of the helix by cysteine, the PA molecules are oriented and their intrinsic dipole moment is tilted with respect to the surface normal, contrary to HOPG. This charge ordering within the SAM fa- cilitates internal electric fields, which obviously renormalize the molec- ular orbital energies along the helix, thus enabling a high conductance through these peptides. [1] K. Kitagawa et al., Journal of Polymer Science Part A: Polymer Chemistry 41, 3493, (2003). [2] Nguyen T.N.Ha et al. The Journal of Physical Chemistry C 123, 612, (2019).