Adsorbed state of furan on Si(111)-7×7 surface studied by X-ray photoelectron spectroscopy

The adsorption of furan on Si(111)-7×7 has been investigated at room temperature and at 90 K using X-ray photoelectron spectroscopy (XPS). The presence of two C 1s photoelectron peaks at room temperature is consistent with the existence of two molecular adsorption states and with a proposed adsorption model of thiophene and furan on Si(111)-7×7, which involves a surface-parallel π-bonded geometry and a σ-bonded geometry through the oxygen atoms. The C 1s photoelectron spectra have also been collected after annealing the sample to 350 K. The effect is the preferential molecular desorption of the surface-parallel π-bonded geometry.