Molecular orientation in octanedithiol and hexadecanethiol monolayers on GaAs and Au measured by infrared spectroscopic ellipsometry.
Infrared spectroscopic ellipsometry was used for determination of molecular orientation and for lateral homogeneity studies of organic monolayers on GaAs and Au, the organic layer being either octanedithiol or hexadecanethiol (HDT). The laterally resolved measurements were performed with the infrared mapping ellipsometer at the synchrotron storage ring BESSY II. The molecular orientation within the monolayers was determined by optical model simulations of the measured ellipsometric spectra. Different tilt angles were obtained for the monolayers of HDT and octanedithiol on GaAs: 19 degrees and >30 degrees , respectively. The tilt angle of the methylene chains for HDT on Au substrate (22 degrees ) is similar to the 19 degrees tilt which was obtained for the HDT monolayers on GaAs, thus suggesting similar molecular ordering of the thiolates on both substrates.
Rosu
Dana M
DM
ISAS-Institute for Analytical Sciences, Department Berlin, Albert-Einstein-Str. 9, 12489 Berlin, Germany. rosu@isas.de
Jones
Jason C
JC
Hsu
Julia W P
JW
Kavanagh
Karen L
KL
Tsankov
Dimiter
D
Schade
Ulrich
U
Esser
Norbert
N
Hinrichs
Karsten
K
D001152:Arsenicals / Q000737:chemistry*; D005708:Gallium / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D013055:Spectrophotometry, Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
D001152:Arsenicals; D008567:Membranes, Artificial; D013438:Sulfhydryl Compounds; C043055:gallium arsenide; C086974:hexadecanethiol; D006046:Gold; D005708:Gallium; C516316:1,8-octanedithiol