The adsorption of pyridine at 200 and 300 K on single-domain Si(100)-$2\times 1$ surfaces at saturation coverage was investigated by means of x-ray photoelectron spectroscopy and angular-dependent near-edge x-ray adsorption fine-structure spectroscopy (NEXAFS). Spectroscopic results are compared with density functional theory calculations. The N 1$s$ NEXAFS spectroscopic signatures of three chemical moieties (dative bond, C–C=N–C and Si–N $sp$${}^3$) are identified. At 200 K all surface products present Si–N bonds (dative bond and Si–N $sp$${}^3$), while at 300 K, C–C=N–C moiety is also detected probing minor species without a Si–N bond. At both temperatures the coexistence of these various species are dominated by 1,4-di-$\sigma$ butterflies (Si–N $sp$${}^3$).

• Received 10 November 2011

DOI:https://doi.org/10.1103/PhysRevB.85.035323