X-ray photoemission spectra of the 2s valence orbitals in cyclic alkanes in relation to valence bands of amorphous Group 4 and 5 elements
The crystalline elements Ge, Si, As, Sb, and Bi display a characteristic two-peak structure in the x-ray photoelectron spectra of their s-like valence bands. In the corresponding amorphous materials the gap between these two bands is filled in. It has been suggested that this is a consequence of topological disorder, i.e., of the existence of odd-membered rings (especially five-membered rings) in the amorphous cases, whereas the crystalline solids contain only six-membered rings. To test this hypothesis we have studied tetrahedrally bonded systems of different ring size in the gas-phase cyclic alkanes. The XPS spectrum of cyclohexane shows a striking resemblance to that of diamond. The other gas-phase spectra can be combined according to different ring-structure models. When this is done, we find that five- and six-membered rings alone are not sufficient to explain the ''filling-in effect'', but that five-, six-, and seven-membered rings are. The topological disorder model of bonding in amorphous semiconductors therefore appears valid. More generally, this work establishes further links between molecular orbital theory and bonding in covalent solids.
- Research Organization:
- Univ. of California, Berkeley
- OSTI ID:
- 7212124
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 99:18
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
ANTIMONY
PHOTOELECTRON SPECTROSCOPY
ARSENIC
BISMUTH
CYCLOALKANES
GERMANIUM
SILICON
CHEMICAL BONDS
ELECTRONIC STRUCTURE
SEMICONDUCTOR MATERIALS
ALKANES
ELECTRON SPECTROSCOPY
ELEMENTS
HYDROCARBONS
METALS
ORGANIC COMPOUNDS
SEMIMETALS
SPECTROSCOPY
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)
400201 - Chemical & Physicochemical Properties
360102 - Metals & Alloys- Structure & Phase Studies
360602 - Other Materials- Structure & Phase Studies