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Title: Effect of Self-Assembled Monolayer Film Order on Nanofriction

Abstract

Self-assembled monolayers have increasingly been explored as potential protective films in devices against friction and adhesion. However, detailed characterization of the monolayer film structure is difficult. This article utilizes a combination of near edge x-ray absorption fine structure (NEXAFS) spectroscopy and Fourier transform infrared (FTIR) spectroscopy to determine the film structure in order to explain the observed nanofriction measurement results. A series of n-alkyltrichlorosilane self-assembled monolayer films with various chain lengths (C5-C30) was prepared on silicon (100) surfaces. Nanofriction measurements were conducted using an atomic force microscope. Results showed that the lowest friction was obtained with a C12 film with higher friction values observed for C5 and C30 films. To explain these observations, the x-ray absorption technique NEXAFS was used to quantitatively measure the surface molecular orientation (order) of these films. It was observed that C12, C16, and C18 films were highly ordered with a molecular orientation of the carbon backbone nearly perpendicular to the surface. C5 and C30 films were less oriented and C10 film showed partial orientation. FTIR spectra suggested that these films possessed different degrees of order. This combination of molecular orientation and order supports and confirms that nanofriction results were heavily influenced by the order andmore » structure of these films.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
913967
Report Number(s):
BNL-78535-2007-JA
Journal ID: ISSN 0734-2101; JVTAD6; TRN: US0801437
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Vac. Sci. Technol., A; Journal Volume: 24; Journal Issue: 4
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ABSORPTION; ADHESION; CARBON; CHAINS; FINE STRUCTURE; FRICTION; ORIENTATION; SILICON; SPECTRA; SPECTROSCOPY; NSLS; national synchrotron light source

Citation Formats

Sambasivan,S., Shieh, S., Fischer, D., and Hsu, S. Effect of Self-Assembled Monolayer Film Order on Nanofriction. United States: N. p., 2006. Web. doi:10.1116/1.2204920.
Sambasivan,S., Shieh, S., Fischer, D., & Hsu, S. Effect of Self-Assembled Monolayer Film Order on Nanofriction. United States. doi:10.1116/1.2204920.
Sambasivan,S., Shieh, S., Fischer, D., and Hsu, S. Sun . "Effect of Self-Assembled Monolayer Film Order on Nanofriction". United States. doi:10.1116/1.2204920.
@article{osti_913967,
title = {Effect of Self-Assembled Monolayer Film Order on Nanofriction},
author = {Sambasivan,S. and Shieh, S. and Fischer, D. and Hsu, S.},
abstractNote = {Self-assembled monolayers have increasingly been explored as potential protective films in devices against friction and adhesion. However, detailed characterization of the monolayer film structure is difficult. This article utilizes a combination of near edge x-ray absorption fine structure (NEXAFS) spectroscopy and Fourier transform infrared (FTIR) spectroscopy to determine the film structure in order to explain the observed nanofriction measurement results. A series of n-alkyltrichlorosilane self-assembled monolayer films with various chain lengths (C5-C30) was prepared on silicon (100) surfaces. Nanofriction measurements were conducted using an atomic force microscope. Results showed that the lowest friction was obtained with a C12 film with higher friction values observed for C5 and C30 films. To explain these observations, the x-ray absorption technique NEXAFS was used to quantitatively measure the surface molecular orientation (order) of these films. It was observed that C12, C16, and C18 films were highly ordered with a molecular orientation of the carbon backbone nearly perpendicular to the surface. C5 and C30 films were less oriented and C10 film showed partial orientation. FTIR spectra suggested that these films possessed different degrees of order. This combination of molecular orientation and order supports and confirms that nanofriction results were heavily influenced by the order and structure of these films.},
doi = {10.1116/1.2204920},
journal = {J. Vac. Sci. Technol., A},
number = 4,
volume = 24,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}