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Electron energy loss analysis for diamond and diamondlike carbon materials

Wang, Ya-Xin
http://rave.ohiolink.edu/etdc/view?acc_num=case1054837163

Abstract Details

1990, PhD, Case Western Reserve University, Physics.
Diamond and diamondlike carbon materials were studied with electron energy loss spectroscopy (EELS). The electron energy losses include the low energy loss range from 0 to 50 eV and the carbon K-edge absorption energy loss range from 250 to 350 eV. The diamond and diamondlike carbon materials include both polycrystalline diamond and the diamondlike carbon samples grown by chemical vapor deposition. Single crystal diamond and graphite were used as a comparison in the energy loss measurement. The properties of diamond and diamondlike carbon materials were analyzed from their characteristic energy loss features. In the low energy loss region, the major losses were caused by the valence electron plasma oscillation losses and the interband transition (from the valence band to the conduction band) losses. In the K-edge absorption energy loss, the 1s electrons were excited to the empty states above the Fermi energy by absorbing the energy from the incident electrons. The distribution of the electronic states in the energy bands were studied from the EELS spectrum. In polycrystalline diamond, a second phase of diamondlike component was observed and the changes of electronic density depended on the relative content of diamondlike component. In hydrogenated diamondlike carbon ( a-C:H), the electronic structure was studied as a function of the ratio of sp3 and sp2 carbon sites and the hydrogen concentration. The structural properties of hydrogenated diamondlike carbon samples were studied from the electron energy loss features. That hydrogen enhances the sp3-bonded carbon sites was directly confirmed from the energy loss spectral analysis. The ratio of sp3 (tetrahedral) to sp2 (trigonal) sites in a-C:H samples increases from 0.29 to 0.75 and the average coordination numbers of each atom decreases from 2.6 to 2.3 as the hydrogen concentration in the samples increase from 28 to 44 at. %. The results of the energy loss measurement were compared to the predictions of the fully constrained covalent network model and the other independent measurements, which were found in good agreement.
R. Hoffman (Advisor)
176 p.
Electron energy loss analysis diamond diamondlike carbon materials

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Citations

  • Wang, Y.-X. (1990). Electron energy loss analysis for diamond and diamondlike carbon materials [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1054837163

    APA Style (7th edition)

  • Wang, Ya-Xin. Electron energy loss analysis for diamond and diamondlike carbon materials. 1990. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1054837163.

    MLA Style (8th edition)

  • Wang, Ya-Xin. "Electron energy loss analysis for diamond and diamondlike carbon materials." Doctoral dissertation, Case Western Reserve University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=case1054837163

    Chicago Manual of Style (17th edition)

case1054837163
597
© 1990, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.