A study of the (001)LiF surface at 80 K by means of diffractive scattering of He and Ne atoms at thermal energies

Boato, G.; Cantini, P.; Mattera, L.

doi:10.1016/0039-6028(76)90381-2

Cited by 233 publications

(54 citation statements)

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“…Previous work by Boato et al suggested the existence of isotopically unique diffraction channels for neon scattering from LiF(001), but was unable to resolve this feature [10]. Here, the separation of the 20 …”

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confidence: 79%

“…Higher ratios of scattered intensity between nonzeroth-order diffraction and specular peaks have been demonstrated to be correlated with increased surface corrugation [10,[20][21][22]. Additionally, the amount of flux that is scattered diffusely from a surface is strongly affected by the surface stiffness, which is quantified by the surface Debye temperature [14,23].…”

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confidence: 99%

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Atom Scattering Picks Out the Heavyweights

Hedgeland

2017

Physics

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The separation of isotopes in space and time by gas-surface atomic diffraction is presented as a new means for isotopic enrichment. A supersonic beam of natural abundance neon is scattered from a periodic surface of methyl-terminated silicon, with the 20 Ne and 22Ne isotopes scattering into unique diffraction channels. Under the experimental conditions presented in this Letter, a single pass yields an enrichment factor 3.50 AE 0.30 for the less abundant isotope, 22 Ne, with extension to multiple passes easily envisioned. The velocity distribution of the incident beam is demonstrated to be the determining factor in the degree of separation between the isotopes' diffraction peaks. In cases where there is incomplete angular separation, the difference in arrival times of the two isotopes at a given scattered angle can be exploited to achieve complete temporal separation of the isotopes. This study explores the novel application of supersonic molecular beam studies as a viable candidate for separation of isotopes without the need for ionization or laser excitation.

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confidence: 79%

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confidence: 99%

Atom Scattering Picks Out the Heavyweights

Hedgeland

2017

Physics

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“…Helium scattering is a valuable nondestructive experimental probe that has been useful for characterizing surface structure [1][2][3][4], measuring surface phonons [5,6], detecting surface impurities [7], and elucidating surface chemical dynamics. Over the past decade, the field has been reinvigorated due to newer, higher-energy helium sources that have allowed observation of diffraction peaks [8] from both insulator [9] (e.g., lithium fluoride) and metallic [10] (e.g., silver) surfaces.…”

Section: Introductionmentioning

confidence: 99%

Approach to coherent interference fringes in helium-surface scattering

Schram

Heller

2018

Phys. Rev. A

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The conventional notion of elastic, coherent atom-surface scattering originates from the scattering particles acting as a quantum-mechanical matter wave, which coherently interfere to produce distinct Bragg peaks which persist at finite temperature. If we introduce inelastic scattering to this scenario, the result is that the surface particles become displaced by the scattering atoms, resulting in emission or absorption of phonons that shift the final energy and momentum of the scatterer. As the lowest-lying phonons are gapless excitations, the ability to measure these phonons is very difficult and this difficulty is exacerbated by the roughly 1-eV resolution found in high-energy helium scattering experiments. Even though the surface has in effect measured the presence of the scatterer which decoheres the particle, we retain the diffraction spots which are referred to as coherent scattering. How do we reconcile these disparate viewpoints? We propose an experiment to more precisely examine the question of coherence in atom-surface scattering. We begin with an initially coherent superposition of helium particles with equal probabilities of interacting with the surface or not interacting with the surface. The beams are directed so that after the scattering event, the atoms are recombined so that we can observe the resulting interference pattern. The degree to which phonons are excited in the lattice by the scattering process dictates the fringe contrast of the interference pattern of the resulting beams. We use semiclassical techniques to simulate and test the viability of this experiment and show that for a wide range of conditions, despite the massive change in the momentum perpendicular to the surface, we can still expect to have coherent (in the superposition sense) scattering.

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“…In experiments on adsorbate sticking on cold surfaces [6][7][8], STM imaging of adsorbate localization [9], surface diffusion and desorption, induced by electron injection from the STM tip [10], a prominently classical behaviour is reported. Adsorbate quantum behaviour on the other hand is examplified by noble gas atom diffraction at solid surfaces [11], molecule tunnelling [12], molecule vibrational and rotational excitation in the STM [13,14], quantum diffusion of hydrogen on tungsten and copper single crystal surfaces [2,15], to mention only a few cases. The transition from quantum to classical behaviour is the essence of decoherence.…”

Section: Introductionmentioning

confidence: 99%

Decoherence Mechanisms in Adsorbate Localization and Diffusion on Solid Surfaces

Drakova

Doyen

2010

e-J. Surf. Sci. Nanotechnol.

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A long standing unsolved puzzle is the wide range of experimentally determined frequency factors for adsorbate diffusion spanning twelve orders of magnitude which are only poorly explained by modern quantum theories of surface diffusion (QTSD) based on ab initio potential energy surfaces (refs. [1]-[4]). This contribution investigates whether decoherence mechanisms, neglected in QTSD, can shed some light on these discrepancies. We suggest a quantum-mechanical theory treating the entanglement of adsorbates with their environment (phonons, electronhole pairs, plasmons, gravitons) [5]. Time dependent wave packet evolution and quantum Zeno effect (permenant "measurement" by specific environmental excitations) are investigated.

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A study of the (001)LiF surface at 80 K by means of diffractive scattering of He and Ne atoms at thermal energies

Cited by 233 publications

References 46 publications

Atom Scattering Picks Out the Heavyweights

Atom Scattering Picks Out the Heavyweights

Approach to coherent interference fringes in helium-surface scattering

Decoherence Mechanisms in Adsorbate Localization and Diffusion on Solid Surfaces

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