Single- and multiphonon atom–surface scattering in the quantum regime

Gumhalter, B.

doi:10.1016/s0370-1573(00)00143-5

Cited by 113 publications

(156 citation statements)

References 275 publications

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“…The question arises how much of the physics might be recovered with a more approximate theory such as distorted wave Born approximation ͑DWBA͒. 35 As presently implemented, 5,7,21 the distorted wave is the solution in the laterally averaged potential V 0 , Eq. ͑7͒, and the absence of SH excitations in the calculations then follows quite directly from a vanishing scalar product Q ជ · ⑀͑Q ជ ,SH͒.…”

Section: Discussionmentioning

confidence: 99%

Excitation of the shear horizontal mode in a monolayer by inelastic helium atom scattering

Bruch

Hansen

2005

The Journal of Chemical Physics

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Inelastic scattering of a low-energy atomic helium beam ͑HAS͒ by a physisorbed monolayer is treated in the one-phonon approximation using a time-dependent wave packet formulation. The calculations show that modes with shear horizontal polarization can be excited near high symmetry azimuths of the monolayer, in agreement with recent experiments. The parameters of the calculations are chosen to match the conditions of HAS experiments for triangular incommensurate monolayer solids of xenon, krypton, and argon adsorbed on the ͑111͒ face of platinum, and the results show many of the systematic experimental trends for relative excitation probability of the shear horizontal and longitudinal acoustic phonon branches. The inelastic scattering at beam energies near 8 meV is exceedingly sensitive to small misalignment between the scattering plane and the high symmetry directions of the monolayer solid. The diffraction and inelastic processes arise from a strong coupling of the incident atom to the target and the calculated results show large departures from expectations based on analogies to inelastic thermal neutron scattering.

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Section: Discussionmentioning

confidence: 99%

Excitation of the shear horizontal mode in a monolayer by inelastic helium atom scattering

Bruch

Hansen

2005

The Journal of Chemical Physics

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“…The effect on the Debye-Waller factor is estimated using the Beeby correction, 19,20 although its reliability at such low energies E i has not been established. 20,21 The magnitudes of the perpendicular components of the wave vector in ⌬k Ќ = ͉k iz ͉ + ͉k fz ͉ are modified to reflect the inner potential:…”

Section: ͑8͒mentioning

confidence: 99%

“…͑14͒. I inel also has a factor k f / k iz , where k f and k iz are the final wave number and perpendicular component of the initial wave vector, 31 and a factor arising from thermally excited phonons in the target monolayer: 20 f q, ͑T͒ ϵ 1 + n͓ ͑q, ͔͒ = 1/͕1 − exp͓− ប ͑q, ͒/k B T͔͖.…”

Section: ͑16͒mentioning

confidence: 99%

“…͑2͒ Similarly, the lateral vibration contributions to the Debye-Waller factor, 17,18 which were small for g = 0, become appreciable for the large ͉g͉ components and modify the distribution of scattered strengths. ͑3͒ For low incident energies, E i Ͻ 8 meV, the magnitude of the attractive potential energy between the atom and the monolayer is comparable to E i and we use the Beeby correction [19][20][21] to estimate the effect of this "inner potential." ͑4͒ The calculations give a large amount of information on the scattering and we introduce statistical characterizations 22,23 to get an overview of the distribution of scattered strengths over channels ͑Appendix B͒.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced creation of dispersive monolayer phonons in Xe∕Pt(111) by inelastic helium atom scattering at low energies

Hansen

Bruch

2007

The Journal of Chemical Physics

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Conditions likely to lead to enhanced inelastic atomic scattering that creates shear horizontal ͑SH͒ and longitudinal acoustic ͑LA͒ monolayer phonons are identified, specifically examining the inelastic scattering of 4 He atoms by a monolayer solid of Xe/ Pt͑111͒ at incident energies of 2 -25 meV. There is strong inelastic scattering for both dispersive phonon branches ͑SH and LA͒ of the monolayer at incident energies below 8 meV. Several improvements enable more complete wave packet calculations of the inelastic scattering than in previous work. Long propagation times are made feasible by adding an absorbing potential at large distance. The times now extend to beyond 100 ps and enable a clarification of processes involving transient trapping of the He atoms. The wave packet is made more monochromatic by significantly increasing the spatial width of the initial Gaussian shape. The narrower energy distribution in the incident beam then enables a demonstration of strong energy dependence of the scattering over a scale of less than 0.3 meV.

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“…Hence, all the results pertaining to vibrations of Xe adlayers on Gr(0001) and several other substrates are at strong variance with the first finding of KKK who obtain that the S-mode in Xe/Gr(0001) exhibits strong dispersion. This type of acoustic-like dispersion is typical of the adlayer modes with longitudinal (L) and shear horizontal (SH) polarisation that couple much weaker to the scattered He atoms 13 and hence their presence cannot explain why in the experiments of inelastic HAS from Xe/Gr(0001) surface 6 the coupling is strongest to an almost dispersionless mode with a frequency of 3.2 meV. Hence, as a consequence of the inappropriate description of Xe adlayer in Ref.…”

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confidence: 97%

Diffraction of He atoms from Xe monolayer adsorbed on the graphite (0 0 0 1) revisited: the importance of multiple scattering processes

Šiber

Gumhalter

2003

Surface Science

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We comment and discuss the findings and conclusions of a recent theoretical study of the diffraction of He atoms from a monolayer of Xe atoms adsorbed on the graphite (0001) surface [Khokonov et al., Surf. Sci. 496(2002)L13]. By revisiting the problem we demonstrate that all main conclusions of Khokonov et al. that pertain to the studied system are at variance with the available experimental and theoretical evidence and the results of multiple scattering calculations presented in this comment.

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Single- and multiphonon atom–surface scattering in the quantum regime

Cited by 113 publications

References 275 publications

Excitation of the shear horizontal mode in a monolayer by inelastic helium atom scattering

Excitation of the shear horizontal mode in a monolayer by inelastic helium atom scattering

Enhanced creation of dispersive monolayer phonons in Xe∕Pt(111) by inelastic helium atom scattering at low energies

Diffraction of He atoms from Xe monolayer adsorbed on the graphite (0 0 0 1) revisited: the importance of multiple scattering processes

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