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

The adsorption of furan on Si(111)-7 x 7 has been investigated at room temp erature and at 90 K using X-ray photoelectron spectroscopy (XPS). The prese nce of two C 1s photoelectron peaks at room temperature is consistent with the existence of two molecular adsorption states and with a proposed adsorp tion model of thiophene and furan on Si(111)-7 x 7, which involves a surfac e-parallel pi-bonded geometry and a sigma-bonded geometry through the oxyge n atoms. The C 1s photoelectron spectra have also been collected after anne aling the sample to 350 K. The effect is the preferential molecular desorpt ion of the surface-parallel x-bonded geometry. (C) 2000 Elsevier Science B. V. All rights reserved.