Phonon dispersion curves of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi mathvariant="normal">Ge</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mn>111</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mtext>−</mml:mtext><mml:mi>c</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:mn>8</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>surface determined by He atom scattering

Lobo, J.; Farı́as, Daniel; Hulpke, E.; Toennies, J. P.; Michel, E. G.

doi:10.1103/physrevb.74.035303

Cited by 12 publications

(4 citation statements)

References 30 publications

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“…Experimental investigation of surface dynam-ics is difficult in general and even more challenging in the case of insulator surfaces. However, scattering experiments with neutral helium atoms upon surfaces have proven to be very well suited for studying surface dynamics [13][14][15]. The technique is strictly surface sensitive with no penetration into the bulk, and the energy of the probing He atoms is in the range of the lowest-energy phonons, thus especially sensitive to these modes.…”

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confidence: 99%

Observation of the Boson Peak at the Surface of Vitreous Silica

et al. 2007

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The boson peak is an excess in the phonon density of states compared to the Debye model that appears in almost all glasses. It has been repeatedly measured in the bulk by a variety of methods, but its origin is still highly debated. Here we present first experimental evidence of the boson peak on the v-SiO2 surface. The measurements were obtained by helium atom scattering. The boson peak appears as a dispersionless mode of approximately 4 meV in the recorded time-of-flight spectra. It is clearly identified as an excess contribution to the low energy Debye-like region in the surface phonon spectral density which is extracted from the time-of-flight spectra using a straightforward theoretical model.

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confidence: 99%

Observation of the Boson Peak at the Surface of Vitreous Silica

et al. 2007

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“…HAS is a powerful tool for investigating the dispersion relation of surface phonons 171,[205][206][207][208][209][210][211][212][213][214] . Conventional supersonic 4 He beams with incident energy Ep in the 10 to 100 meV range have energy resolution of the order of Ep/E  10 2 , which allows exploring the low acoustic range of surface phonons, hardly accessible to HREELS 215 .…”

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confidence: 99%

Spectroscopic Investigations of Phonons in Epitaxial Graphene

Politano

2016

Critical Reviews in Solid State and Materials Sciences

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The interaction of graphene with metallic substrates reveals phenomena and properties of great relevance for applications in nanotechnology. In this review, the vibrational characterization by means of various inelastic scattering spectroscopies are surveyed for graphene epitaxially grown on metals and transition carbides. In particular, the manifestations of electron-phonon interaction, such as Kohn anomalies, the evaluation of elastic properties and the nanoscale control of phonon modes are presented and discussed. Abbreviations AFM atomic-force microscopy ARPES angle-resolved photoemission spectroscopy BZ Brillouin zone CVD chemical vapor deposition DFT density functional theory DOS density of states EPC electron-phonon coupling FC force constant GGA generalized gradient approximations HAS helium atom scattering HREELS high-resolution electron energy loss spectroscopy LDA local-density approximation LEED low-energy electron diffraction LEEM low-energy electron microscopy MLG monolayer graphene MWCNT multi-walled carbon nanotube STM scanning tunneling microscopy STM-IETS STM-inelastic electron tunnelling spectroscopy STS scanning tunneling spectroscopy SWCNT single-walled carbon nanotube

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“…Helium atom scattering (HAS) is a strictly surface sensitive technique with no penetration into the bulk. While experimental investigation of surface dynamics is difficult in general and even more challenging in the case of insulator surfaces, HAS has proven to be very well suited for looking at surface vibrational properties [1][2][3]. The probing He atoms impinge on the surface with kinetic energy in the range of the lowest energy phonons, and thus are especially sensitive to these modes.…”

Section: Introductionmentioning

confidence: 99%

Vibrational excitations of glass observed using helium atom scattering

Steurer¹,

Apfolter²,

Koch³

et al. 2008

J. Phys.: Condens. Matter

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In this paper we demonstrate a new application of helium atom scattering: the investigation of amorphous solids. Recently, we observed an excess density of states in the vibrational spectrum of the vitreous silica surface using inelastic He atom scattering. A surface phonon spectral density was readily extracted from the recorded data and the excess density of states was attributed to the surface manifestation of the boson peak phenomenon of disordered structures. Here we present further data analysis and show that the intensity of the surface boson peak at constant energy, i.e., ρzz(ΔE = const,ΔK)/ρDebye, strongly depends upon the parallel momentum transfer with a maximum in the neighborhood of ≈1 nm−1. In contrast, the position of the maximum intensity of the surface boson peak shows negligible ΔK dependence and is seen as a dispersionless mode at 3.7 ± 0.4 meV. Measurements of the width of the surface boson peak are also presented.

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Phonon dispersion curves of theGe(111)−c(2×8)surface determined by He atom scattering

Cited by 12 publications

References 30 publications

Observation of the Boson Peak at the Surface of Vitreous Silica

Observation of the Boson Peak at the Surface of Vitreous Silica

Spectroscopic Investigations of Phonons in Epitaxial Graphene

Vibrational excitations of glass observed using helium atom scattering

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