Hydroxyl group-induced adsorptions of 4-nitro benzoic acid on the Si(1Â 0Â 0) surface

The adsorption of 4-NO2(C6H4)COOH (4-nitro benzoic acid) on the in situ prepared OH/Si(1 0 0) 2 × 1 surface was investigated using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS). XPS and NEXAFS results reveal that one 4-nitro benzoic acid (4-NBA) adsorbs on a OH group on the Si(1 0 0) through C-O-Si linkage induced by a dehydrating reaction between OH on the Si(1 0 0) and OH in the carboxyl group. Upon irradiating 4-NBA/OH/Si(1 0 0) surface by photons of 0.24 mJ/(s cm2) (600 eV monochromatic beam), NO2 moiety in the molecule was desorbed, whereas the phenyl ring and carboxyl group remained intact. The irradiation by the photon of 156.4 mJ/(s cm2) (0th order beam) resulted in destruction of molecules on the surface and metathesis of NO2 into NH2.