In situ attenuated total reflection FTIR investigations of thin water films in the silanization of ZnSe and Si

In situ attenuated total reflection ATR-FTIR spectroscopy is used to investigate the reaction of trimethylchlorosilane (CH3)(3)SiCl in organic solvents at room temperature on ZnSe and on Si surfaces in the presence and absence of pyridine. In the absence of the base, siloxanes are formed, but they can be removed in situ with the reaction solvent along with the surplus of trimethylchlorosilane and no chemisorption is detected. Instead a thin water film is formed on the surface which shows a well resolved ATR-IR water spectrum with absorptions v(as)(O-H) at 3477 cm(-1), v(s)(O-H) at 3421 cm(-1), 2 delta(H-O-H) at 3186 cm(-1), 6(H-O-H) + v(L) at 2182 cm(-1) where nu(L) is a librational mode of water and delta(H-O-H) at 1601 cm(-1). These thin water films are astonishingly stable and easy to handle, and their growth can be monitored. Addition of pyridine to the reaction solvent allows the detection of trimethylsilanol with an absorption band at 3706 cm(-1). Concurrently pyridinium chloride is formed and partly precipitates on the substrate surface. (C) 1997 Elsevier Science B.V.