Sulfur L{sub 2,3} and zinc M{sub 2,3} soft-x-ray fluorescence spectra in CdS and ZnS
- University of Tennessee, Knoxville, Tennessee 37996 (United States)
- Tulane University, New Orleans, Louisiana 70118 (United States)
- Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)
The sulfur L{sub 2,3} soft-x-ray emission spectra of wurtzite CdS and cubic ZnS and the zinc M{sub 2,3} spectra of ZnS have been measured using both photon and electron-beam excitation. The photon-excited sulfur L spectra are found to be much sharper than electron-beam-excited spectra. Using photon excitation between the L{sub 2} and L{sub 3} thresholds, a pure L{sub 3} spectrum is obtained for both materials. Broad features of the S L spectra, consisting of a lower valence band (LVB) derived from the sulfur 3s orbital and an upper valence band (UVB) derived from S 3p and Cd(Zn) s and p orbitals, are typical of materials with mixed ionic-covalent character. A narrow band between the UVB and LVB is associated with overlap of Zn 3d and Cd 4d orbitals onto the S site. The s+d local partial density of states derived from these spectra provide a rigorous test of band-structure calculations; they are in good agreement for the position, width, and structure of the LVB and UVB, but place the d band deeper in the subband gap than theory predicts. The Zn M{sub 2,3} spectrum has large lifetime broadening and thus provides limited information. However, near-threshold excitation of this spectrum shows dramatic effects resulting from an electronic resonance Raman process. {copyright} {ital 1997} {ital The American Physical Society}
- OSTI ID:
- 467367
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 8 Vol. 55; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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