Web Release Date: January 4,
Modification of Alkaneselenolate Monolayers by Low-Energy Electrons
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Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany, Department of Chemical and Biological Sciences and Engineering, Polytechnic University, Six Metrotech Center, Brooklyn, New York, and Department of Chemistry, Bar-Ilan University, Ramat Gan 52900, Israel 2
Received: September 9, 2007
In Final Form: October 25, 2007
Abstract:
The effect of low-energy (50 eV) electron irradiation on alkaneselenolate (AS) self-assembled monolayers (SAMs) was studied by synchrotron-based X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. As a test system, SAMs of dodecaneselenolate (C12Se) were used, and an analogous dodecanethiolate (C12S) SAM was taken as a reference. Both the alkyl matrix and headgroup-substrate interface in AS SAMs were found to be affected by a variety of closely interrelated irradiation-induced processes, which mostly follow a pseudo first-order kinetics and level off at high irradiation doses. The cross-sections of the most prominent processes were obtained and found to be in a range of 2-3 × 10-16 cm2. The values are very close to the parameters for analogous alkanethiolate (AT) SAMs, which exhibit similar behavior upon exposure to low-energy electron irradiation. At the same time, the saturation values of the fingerprint parameters for some irradiation-induced processes in AS SAMs appeared to be slightly smaller than the values for analogous AT films. This is explained by a stronger headgroup-substrate bond in the case of selenium.
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