Effect of chain length on the adhesion behaviour of n-alkanethiol self-assembled monolayers on Au(111): An atomic force microscopy study

Subramanian, S and Sampath, S (2005) Effect of chain length on the adhesion behaviour of n-alkanethiol self-assembled monolayers on Au(111): An atomic force microscopy study. In: Pramana-journal of physics, 65 (4). pp. 753-761.

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Abstract

The effect of chain length on the adhesion behaviour of n-alkanethiols $CH_{3}(CH_{2})_{n}SH$, where n = 5, 6, 7, 9, 10, 11, 14 and 15 has been followed by carrying out pull-off force measurement using atomic force microscopy (AFM). The self-assembled monolayers on Au(111) surface has been characterized by reflection absorption infra-red spectroscopy(RAIRS) and contact mode AFM. It is observed that the work of adhesion is independent of thiol chain length though the standard deviation is high for short chain length thiol-based monolayers. This may be attributed to the relatively more deformable nature of the short chainthiol films due to their heterogeneity in the monolayer structure than the long chain ones. This, in turn,increases the contact area/volume between the AFM tip and the monolayer, and hence the force of adhesion.However, in the presence of water, the force of adhesion is lower than that observed in air reflecting the effects of capillary forces/polar components associated with the surface energy.

Item Type:	Journal Article
Publication:	Pramana-journal of physics
Publisher:	Indian Academy of Sciences
Additional Information:	Copyright for this article belongs to Indian Academy of Sciences.
Keywords:	Adhesion;alkanethiols;atomic force microscopy;force
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	17 Nov 2005
Last Modified:	19 Sep 2010 04:21
URI:	http://eprints.iisc.ac.in/id/eprint/4040

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