Abstract
High-resolution electron-energy-loss spectra of ultrathin (d<3 nm) LiBr epitaxial films on Si(100) [W. Gao et al., Solid State Commun. 87, 1013 (1993)] reveal an anomalous dependence of the frequencies of the macroscopic surface phonons on the layer thickness d. We present lattice-dynamics calculations of the spectra which prove that this anomalous dependence arises from the excitation of standing-wave optical phonons confined in the film and reflects the dispersion relation of bulk optical vibrations of LiBr in the direction normal to the surface.
Original language | English |
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Pages (from-to) | 570-573 |
Number of pages | 4 |
Journal | Physical review letters |
Volume | 74 |
Issue number | 4 |
DOIs | |
Publication status | Published - 1995 |