IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS+BI-TuM

Paper SS+BI-TuM9
Odd-Even Effects in the Electron-induced Damage of Biphenyl-substituted Alkanethiol Self-assembled Monolayers

Tuesday, October 30, 2001, 11:00 am, Room 120

Session: Poirier Memorial Session: Self-Assembled Monolayers I
Presenter: M. Zharnikov, Universität Heidelberg, Germany
Authors: M. Zharnikov, Universität Heidelberg, Germany
S. Frey, Universität Heidelberg, Germany
H.-T. Rong, Universität Heidelberg, Germany
M. Buck, University of St Andrews, U.K.
K. Heister, Universität Heidelberg, Germany
M. Grunze, Universität Heidelberg, Germany
Correspondent: Click to Email
Self-assembled monolayers (SAMs) formed on Au(111) from biphenyl-substituted alkanethiols CH@sub 3@(C@sub 6@H@sub 4@)@sub2@(CH@sub 2@)@sub n@SH (BPn) exhibit odd-even changes in the packing density and the tilt angle of the biphenyl moieties with varying length of the aliphatic part. We have applied X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, infrared absorption spectroscopy, and advancing contact angle measurements to study electron beam induced damage in these systems as well as in pure aromatic biphenylthiol (BP0) SAMs on Au substrates. Although the character of the electron-induced damage in all investigated SAMs was found to be similar, the extent and rate of the observed changes exhibited a clear correlation with the packing density and orientation of the biphenyl moieties in the BPn SAMs: The densely packed BPn films are noticeably more insensitive (in terms of the orientational order, irradiation-induced desorption, and anchoring to the substrate) towards electron irradiation than the loosely packed BPn layers. The extent of the irradiation-induced damage in pure aromatic BP0 SAMs was observed to be very close to that in the loosely packed BPn films, which indicates that the former films are in some sense also "loosely packed". Considering the potential applications of the aromatic SAMs as lithographic resist or template, the introduction of the short aliphatic chain in the respective molecules provides a simple and efficient way to manipulate their reaction toward ionizing irradiation in a desirable way. This work has been supported by the German BMBF (05 SF8VHA 1).