Figures from "Structure and Bonding of Ordered Organic Monolayers of 1,3,5,7-Cyclooctatetraene on the Si(100) Surface: Surface Cycloaddition Chemistry of an Anti-aromatic Molecule", by J.S. Hovis and R.J. Hamers, Journal of Physical Chemistry B, vol. 102, no. 4, pp. 687-692 (January 22, 1998)

© 1998 American Chemical Society

Note: All the figures shown here have been published and copyrighted. If you use or reproduce any of these figures in any way, you must indicate the original source of the image. For electronic or paper publication, you must receive written permission from Robert Hamers and the American Chemical Society.

Figure 1

Scanning tunneling microscopy images of the Si(001) surface after saturation exposure to 1,3,5,7-cyclooctatetraene. Images were obtained with a sample bias of -2.2 V and a tunneling current of 150 pA.
(1a) Large area image with a single height step propagating horizontally through the center of the image.
(1b) High-resolution image showing the adsorption pattern of COT molecules.
(1c) High-resolution image showing the presence of a second minority species ("D") on the surface along with the majority species.

Figure 2

(2a) STM image of Si(001) after exposure to 0.1 Langmuir (1x10-8 torr for 10 seconds) 1,3,5,7-cyclooctatetraene. Image was obtained with a sample bias of -2.0 V and a tunneling current of 200 pA; image size 70 Å x 46 Å.
(2b) Height profile measured along the line indicated by arrows in fig. 2a.

Figure 3

Infrared absorption spectra of Si(100) exposed to COT and to COD. Schematic depiction of incident electric field vector with respect to the Si(001) surface. Absorption spectra of Si(100) surface exposed to saturation coverage (3x10-8 torr, 100 seconds) of 1,3,5,7-cyclooctatetraene (COT), and Si(100) surface exposed to saturation coverage (3x10-8 torr, 166 seconds) of 1,5-cyclooctadiene (COD). The figure shows the C-H stretching region (2800-3100 cm-1) and the Si-H stretching region (2000-2200 cm-1).

Figure 4

Possible geometries for bonding of COT to Si(001) surface.

(4a) Geometry of free COT molecule.
(4b) Diels-Alder [4+2] cycloaddition reaction for planar COT reacting with Si(001).
(4c) [2+2] addition reaction involving only one C=C group in di-sigma configuration.
(4d) [2+2] addition reaction involving two C=C groups in cross-dimer configuration.
(4e) [2+2] addition reaction involving two C=C groups in di-sigma configuration.
(4f) 15-atom cluster used for ab initio molecular orbital calculations. Terminating hydrogen atoms at cluster edges are not shown.

Last updated January 29, 1998