Quantitative measurements of frictional properties of n-alkanethiols on Au(111) by scanning force microscopy

Citation
Ly. Li et al., Quantitative measurements of frictional properties of n-alkanethiols on Au(111) by scanning force microscopy, J PHYS CH B, 103(39), 1999, pp. 8290-8295
Citations number
42
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
15206106 → ACNP
Volume
103
Issue
39
Year of publication
1999
Pages
8290 - 8295
Database
ISI
SICI code
1520-6106(19990930)103:39<8290:QMOFPO>2.0.ZU;2-E
Abstract
We present a quantitative study of the frictional properties of self-assemb led alkanethiol monolayers on Au-(111) as a function of chain length using scanning force microscope, The lateral and normal forces are calibrated in situ using a combination of the two-slope method proposed by Ogletree ct al , and the added mass method proposed by Cleveland er nl. The comparative st udy of the same system by another calibrated Si3N4 tip was carried out. The friction coefficients for the same alkanethiol system, but with different tips, differ by less than 15%, indicating the reliability of nanoscale fric tional and normal force measurements using a scanning force microscope. An in situ experimental force calibration for each cantilever is needed in old er to perform absolute force measurements. Our results also show that frict ional fords depend strongly on the number of carbon atoms in the alkane cha in. The friction coefficient of alkanethiol decreases as the chain length i ncreases and is lower than that of a bare Au(lll) surface.