COLL 226 |
| Thermal deposition of gold (in ultrahigh vacuum) on monolayers of 3-mercaptopropyltrimethoxysilane (MPTS) on hydroxylated silicon oxide surfaces was investigated using X-ray and ultraviolet photoelectron spectroscopies (XPS and UPS). This adsorbate is interesting because it has the ability to bond to two different surfaces, offering the possibility of forming metal-organic-semiconductor sandwiches. Gold-thiolate bond formation is evidenced by appearance of an S2p peak at 162.4 eV, and C1s and Au4f XPS intensities indicate that the gold stays on top of the monolayer. UPS has been used to measure the valence states of the surface, and work functions have been determined from the UPS spectral widths. A work function decrease of 1.1 eV is observed for metal doses between 0 and 2 monolayers, and the work function approaches 4.4 eV once the metal dose exceeds 2 monolayers. Atomic force microscopy force-distance measurements between a gold tip and MPTS surface suggest gold-thiol bond formation. |
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Fundamental Research in Colloid and Surface Chemistry
6:00 PM-8:00 PM, Monday, August 20, 2007 BCEC -- East Registration, Poster
Division of Colloid & Surface Chemistry |