In situ study of nitrobenzene grafting on Si(1 1 1)-H surfaces by infrared spectroscopic ellipsometry

The binding of nitrobenzene (NB) molecules from a solution of 4-nitrobenzene-diazonium-tetrafluoroborate on a Si(1 1 1)-H surface was investigated during the electrochemical processing in diluted sulphuric acid by means of infrared spectroscopic ellipsometry (IR-SE). The grafting was monitored by an increase in specific IR absorption bands due to symmetric and anti-symmetric NO2 stretching vibrations in the 1400–1700 cm−1 regime. The p- and s-polarized reflectances were recorded within 20 s for each spectrum only. NB molecules were detected when bonded to the Si(1 1 1) surface but not in the 2 mM solution itself. Oxide formation on the NB grafted Si surface was observed after drying in inert atmosphere and not during the grafting process in the aqueous solution.