Tetra-σ bonding adsorption of pyridine on Si(1 0 0)-2 × 1

We studied adsorption of pyridine on Si(1 0 0) at room temperature using high resolution photoemission spectroscopy (PES) and near edge X-ray adsorption fine structure (NEXAFS) in the partial electron yield (PEY) mode. The Si 2p, C 1s, N 1s spectra of pyridine on Si(1 0 0) showed that pyridine is chemisorbed on Si(1 0 0)-2 × 1 through the formation of the tetra-σ-bonded structure with the N atom and three C atoms. NEXAFS was conducted to characterize the adsorption geometry of pyridine on Si(1 0 0). The π* orbital of CC bond showed a good angle dependence in C K-edge NEXAFS spectra, and we were able to estimate the adsorption angle between chemisorbed pyridine of CC bond and the Si(1 0 0) surface using an analytical solution of NEXAFS intensity. We find the coexistence of two different tight bridges with the adsorption angles 42 ± 2° and 45 ± 2° with almost equal abundance.