INVESTIGADORES
ASCOLANI Hugo Del Lujan
congresos y reuniones científicas
Título:
Local structure determination of NH2 on Si(111)(7x7)
Autor/es:
S. BENGIÓ; H. ASCOLANI; N. FRANCO; J. AVILA; M.C. ASENSIO; A.M. BRADSHAW; D.P. WOODRUFF
Lugar:
Centro Atómico Bariloche, Bariloche
Reunión:
Congreso; Primer Encuentro de Física y Química (FyQS I); 2004
Institución organizadora:
Centro Atómico Bariloche
Resumen:
To understand surface chemistry we need to find answers to some questions regarding issues such us the structure of the surface, the adsorption sites, the mechanism of the reaction and how it relates to the local electronic structure, etc. To experimentally determine the adsorption sites is ussually difficult because defects and dissordered phases are often involved in surface reactions. Such phases are not appropiate for study by long-range-order diffraction techniques. In this work we have applied photoelectron diffraction, a local technique, to determine the adorption site of adsorbed NH2 species on Si(111)(7x7) resulting from reaction with NH3 at room temperature. [1] The results show that NH2 is adsorbed (almost) exclusively atop Si surface rest atoms with a Si-N bondlength of 1.71± 0.02 Å and very little modification of the geometry of the Si atoms in the layer below. Any coadsorbed NH on the surface is either of low relative coverage or is also adsorbed in local atop sites. There is evidence that a small fraction (8± 7%) of the NHx species may occupy sites atop Si surface adatoms. [1] S. Bengió, et al., Phys. Rev. B 69, 125340 (2004).