ISSN:
1432-0630
Keywords:
81.15.Fg
;
68.55.Nq
;
71.25.Mg
;
82.65.My
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Abstract Amorphous carbon (a-C) films obtained by pulsed-laser ablation of graphite have been investigated by X-ray Absorption Spectroscopy (XAS). The onset of 1s →σ * transitions in the films lies in the gap between theπ * andσ * bands in graphite and very close to the absorption edge of diamond, indicating a high content ofsp 3 hybridization. A sharp feature at this onset is observed and assigned to a core exciton insp 3-hybridized disordered C atoms. Its shift of 0.5 eV with respect to the core exciton in diamond is probably due to a higher localization of the excited electron induced by disorder. A small peak coming from C−H bonds at the surface is observed and its intensity inereases with the amount ofsp 3-hybridized atoms in the sample. This can be easily explained by associating a higher amount of dangling bonds at the surface to a highersp 3 content. Polarization-dependent XAS measurements show that the angular distribution of these C−H bonds has a mean value close to the normal to the surface.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01538374
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