Adsorbate-surface phonon interactions in deuterium-passivated Si(111)-(1 × 1)

G. A. Ferguson, Krishnan Raghavachari, David J. Michalak, Yves Chabal

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11 Scopus citations


The vibrational spectra of atomically flat hydrogen- and deuterium-passivated Si(111)-(1 × 1) surfaces are investigated using theoretical and experimental techniques. An unexpected isotopic shift is observed for the Si-H bending mode when hydrogen is replaced with deuterium, with δ(Si-H) = 626 cm-1 and δ(Si-D) = 537 cm -1. The Si-H stretching mode, in contrast, behaves as expected with v(Si-H) = 2083 cm-1 and v(Si-D) = 1516 cm-1. Density functional studies reveal that the mode observed at 537 cm-1 is mostly a phonon mode, which results from the coupling of near-surface phonons with the lower frequency bending mode of the deuterated surface. This coupling causes a shift in the ordering of the expected vibrational modes when hydrogen is replaced by deuterium. We also suggest that such a mode around 535 cm -1 should be seen for many other surfaces and is a general feature of many monovalently terminated Si(111) surfaces.

Original languageEnglish (US)
Pages (from-to)1034-1039
Number of pages6
JournalJournal of Physical Chemistry C
Issue number4
StatePublished - Jan 31 2008

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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