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.
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Bonding of cycloalkenes to Si(100)-(2 × 1). A silicon dimer, depicted as Si=Si, reacts with a C=C bond to form a pair of C-Si bonds. The proposed structures are most consistent with experiments; multiple products are possible for polyenes. |
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Figure 2Topographic (constant current) images at -2.5 V sample bias and 2 nA current. (a) Cyclopentene and a few cyclooctenes. (b) cis-Cyclooctene and 1,5-cyclooctadiene. (c) 1,3,5,7-Cyclooctatetraene. Insets identify typical images for each molecule. The inset structures are the molecules as dosed, before reaction on the surface. One or more C=C bond is converted to C-C in the product. |
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Figure 3Bias-dependent images. The top and bottom images in each pair were taken simultaneously with different bias on alternate scan lines. (a) Mixture of cyclopentene and cyclooctatetraene. Top -2.5 V, bottom -1.25 V. (b) Mixture of cyclooctene and cyclooctadiene. Top -2.25 V, bottom -1.25 V. (c) Cyclooctatetraene. Top -3.0 V, bottom -1.0 V. |
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Figure 4
The apparent barrier is reduced over the adsorbates. (a) Topographic image of cyclopentene molecules. (b) Barrier height image taken simultaneously. (c) Change in apparent barrier height relative to bare silicon along the section in (b). The values are approximate.
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Figure 5
Energy levels for bare silicon (a) and the reacted surface (b). This figure is highly schematic; the abscissa mixes density-of-states and distance. At -1 V bias, only the dimer |
Last updated Dec. 19, 1998