Date of Award
Chemistry and Biochemistry
A polished zinc selenide (ZnSe) substrate was characterized using X-ray photoelectron spectroscopy (XPS) in order to investigate the nature of the polished surface and the way the chemistry of the surface changes when a selfassembled monolayer (SAM) is adsorbed on the surface. The formation of the SAM on ZnSe was indicated by static contact angles of 93° (±2) for a thiolate SAM and 94° (±2) for a carboxyl SAM. In addition, a characteristic methylene FTIR peak at 2917 cm-1 and 2916 cm-1 for the thiolate and carboxylate SAMs respectively confirmed the presence of SAMs. The XPS results indicate that the polished surface is significantly oxidized and analysis of fracture surfaces show that the oxide forms quickly under ambient conditions. As might be expected, cleaning the surface in a UV-Ozone chamber (UVOC) in preparation for adsorption of an organic monolayer increases the concentration of the oxide at the surface. After adsorption of thiolate or carboxylate SAMs, a significant decrease in the surface oxide was observed, particularly the zinc oxide as measured by a shift in the zinc auger parameter for the carboxylate SAM and a decrease in the oxygen 1s peak. A decrease in the selenium 3d 5/2 and 3/2 oxide peak was also observed.
Mellott, Emily J.; Bojan, Vince; and Noble, Alison R., "Analysis of Adsorbates on Polished Zinc Selenide" (2014). Honors Projects and Presentations: Undergraduate. 205.