Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

Vos, M.; Marmitt, G. G.; Finkelstein, Y.; Moreh, R.

doi:10.1063/1.4929911

Title: Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra

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Abstract

Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensitymore »« less

Authors:

Vos, M. ^[1]; Marmitt, G. G. ^[1]; Finkelstein, Y. ^[2]; Moreh, R. ^[3]

Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra ACT (Australia)
Nuclear Research Center — Negev, Beer-Sheva 84190 (Israel)
Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

Publication Date:: Mon Sep 14 00:00:00 EDT 2015

OSTI Identifier:: 22489564

Resource Type:: Journal Article

Journal Name:: Journal of Chemical Physics

Additional Journal Information:: Journal Volume: 143; Journal Issue: 10; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CALCIUM CARBONATES; COMPARATIVE EVALUATIONS; DOPPLER BROADENING; ELECTRONS; ENERGY-LOSS SPECTROSCOPY; EV RANGE; EXCITATION; KINETIC ENERGY; LITHIUM CARBONATES; MULTIPLE SCATTERING; PEAKS; SILICA; SILICON OXIDES; SPECTRA

Citation Formats


                    Vos, M., Marmitt, G. G., Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS, Finkelstein, Y., and Moreh, R. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra.  United States: N. p., 2015. 
        Web.  doi:10.1063/1.4929911.

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                    Vos, M., Marmitt, G. G., Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS, Finkelstein, Y., & Moreh, R. Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra.  United States.  https://doi.org/10.1063/1.4929911

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                    Vos, M., Marmitt, G. G., Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS, Finkelstein, Y., and Moreh, R. 2015.  
        "Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra".  United States.  https://doi.org/10.1063/1.4929911.

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@article{osti_22489564,

  title        = {Determining the band gap and mean kinetic energy of atoms from reflection electron energy loss spectra},

  author       = {Vos, M. and Marmitt, G. G. and Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970 Porto Alegre, RS and Finkelstein, Y. and Moreh, R.},

  abstractNote = {Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E − E{sub gap}){sup 1.5}. For CaCO{sub 3}, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li{sub 2}CO{sub 3} (7.5 eV) is the first experimental estimate.},

  doi          = {10.1063/1.4929911},

  url          = {https://www.osti.gov/biblio/22489564},
  journal      = {Journal of Chemical Physics},

  issn         = {0021-9606},

  number       = 10,

  volume       = 143,

  place        = {United States},

  year         = {Mon Sep 14 00:00:00 EDT 2015},

  month        = {Mon Sep 14 00:00:00 EDT 2015}

}

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