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Debiossac M, Pan P, Roncin P. Elastic and inelastic diffraction of fast neon atoms on a LiF surface. Phys Chem Chem Phys 2023; 25:30966-30974. [PMID: 37937541 DOI: 10.1039/d3cp04034h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Grazing incidence fast atom diffraction has mainly been investigated with helium atoms, considered as the best possible choice for surface analysis. This article presents experimental diffraction profiles recorded with neon projectile, between 300 eV and 4 keV kinetic energy with incidence angles θi between 0.3 and 1.5° along three different directions of a LiF(001) crystal surface. These correspond to perpendicular energy ranging from a few meV up to almost 1 eV. A careful analysis of the scattering profile allows us to extract the diffracted intensities even when inelastic effects become so large that most quantum signatures have disappeared. The relevance of this approach is discussed in terms of surface topology.
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Affiliation(s)
- Maxime Debiossac
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France.
| | - Peng Pan
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France.
| | - Philippe Roncin
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France.
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2
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Pan P, Rad JN, Roncin P. A setup for grazing incidence fast atom diffraction. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:093305. [PMID: 36182520 DOI: 10.1063/5.0099269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 08/05/2022] [Indexed: 06/16/2023]
Abstract
We describe a UHV setup for grazing incidence fast atom diffraction (GIFAD) experiments. The overall geometry is simply a source of keV atoms facing an imaging detector. Therefore, it is very similar to the geometry of reflection high energy electron diffraction experiments used to monitor growth at surfaces. Several custom instrumental developments are described making GIFAD operation efficient and straightforward. The difficulties associated with accurately measuring the small scattering angle and the related calibration are carefully analyzed.
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Affiliation(s)
- Peng Pan
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France
| | - Jaafar Najafi Rad
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France
| | - Philippe Roncin
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France
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3
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Del Cueto M, Muzas AS, Martín F, Díaz C. Stereodynamics effects in grazing-incidence fast-molecule diffraction. Phys Chem Chem Phys 2022; 24:19541-19551. [PMID: 35938887 DOI: 10.1039/d2cp02109a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Grazing-incidence fast-projectile diffraction has been proposed both as a complement and an alternative to thermal-energy projectile scattering, which explains the interest that this technique has received in recent years, especially in the case of atomic projectiles. On the other hand, despite the richer physics involved, molecular projectiles have received much less attention. In this work, we present a theoretical study of grazing-incidence fast-molecule diffraction of H2 from KCl(001) using a six-dimensional density functional theory based potential energy surface and a time-dependent wavepacket propagation method. The analysis of the computed diffraction patterns as a function of the molecular alignment, and their comparison with the available experimental data, where the initial distribution of rotational states in the molecule is not known, reveals a puzzling stereodynamics effect of the diffracted projectiles: diffracted molecules aligned perpendicular, or quasi perpendicular, to the surface reproduce rather well the experimental diffraction pattern, whereas those molecules aligned parallel to or tilted with respect to the surface do not behave as in the experiments. These results call for more detailed investigations of the molecular beam generation process.
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Affiliation(s)
- M Del Cueto
- Department of Chemistry, University of Liverpool, Liverpool, L69 3BK, UK
| | - A S Muzas
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donotia-San Sebastián, Spain
| | - F Martín
- Departamento de Química Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain.,Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain.,Instituto Madrileño de Estudios Avanzado en Nanociencia (IMDEA-Nanociencia), Cantoblanco 28049, Madrid, Spain
| | - C Díaz
- Departamento de Química Física, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
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4
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Díaz C, Gravielle MS. Grazing incidence fast atom and molecule diffraction: theoretical challenges. Phys Chem Chem Phys 2022; 24:15628-15656. [PMID: 35730987 DOI: 10.1039/d2cp01246d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This perspective article reviews the state-of-the-art of grazing incidence fast atom and molecule diffraction (GIFAD and GIFMD) simulations and addresses the main challenges that theorists, aiming to provide useful inputs in this topic, are facing. We first discuss briefly the methods used to build accurate potential energy surfaces describing the interaction between the projectile and the surface. Subsequently, we focus on the dynamics simulation methods for GIFAD, a phenomenon that has received a lot of experimental attention since 2007, when the first measurements were published. Following this experimental effort, theorists have developed and adapted a bunch of methods able to simulate, analyze and extract information from the experimental outputs. We review these methods, from the very simple ones based on classical dynamics to the full quantum ones, paying special attention to more versatile semiclassical approaches, which include quantum ingredients in the dynamics at a computational cost only slightly higher than that required in classical dynamics. Within the semiclassical framework it is possible, for example, to include in the dynamics the surface phonons and the projectile coherence, two factors that may have a relevant influence on the experimental measurements, at a reasonable computational cost. Finally, we address GIFMD, a phenomenon that has received much less attention and for which there is still a lot of room for research. We review the few examples of GIFMD available in the literature, and we discuss new phenomena associated with the molecular internal degrees of freedom, which may have some impact in other closely related fields, such as molecular reactivity on metal surfaces. Finally, we point out opened questions, raised from the comparisons between theoretical and experimental results, which claim for further experimental efforts.
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Affiliation(s)
- Cristina Díaz
- Departamento de Química Física, Facultad de CC. Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
| | - María Silvia Gravielle
- Instituto de Astronomía y Física del Espacio (IAFE, UBA-CONICET), Ciudad Universitaria, C1428EGA, Buenos Aires, Argentina.
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5
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Pan P, Debiossac M, Roncin P. Temperature dependence in fast-atom diffraction at surfaces. Phys Chem Chem Phys 2022; 24:12319-12328. [PMID: 35545937 DOI: 10.1039/d2cp00829g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Grazing incidence fast atom diffraction at crystal surfaces (GIFAD or FAD) has demonstrated coherent diffraction both at effective energies close to one eV (λ⊥ ≈ 14 pm for He) and at elevated surface temperatures offering high topological resolution and real time monitoring of growth processes. This is explained by a favorable Debye-Waller factor specific to the multiple collision regime of grazing incidence. This paper presents the first extensive evaluation of the temperature behavior between 177 and 1017 K on a LiF surface. Similarly to diffraction at thermal energies (TEAS), an exponential attenuation of the elastic intensity is observed but, contrarily to TEAS, the maximum coherence is not directly reduced by the attraction forces that increase the effective impact energy. It is more influenced by the surface stiffness and appears very sensitive to surface defects.
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Affiliation(s)
- Peng Pan
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France
| | - Maxime Debiossac
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France
| | - Philippe Roncin
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France
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Tamtögl A, Ruckhofer A, Campi D, Allison W, Ernst WE. Atom-surface van der Waals potentials of topological insulators and semimetals from scattering measurements. Phys Chem Chem Phys 2021; 23:7637-7652. [PMID: 33492313 DOI: 10.1039/d0cp05388k] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The phenomenology of resonant scattering has been known since the earliest experiments upon scattering of atomic beams from surfaces and is a means of obtaining experimental information about the fundamentals of weak adsorption systems in the van der Waals regime. We provide an overview of the experimental approach based on new experimental data for the He-Sb2Te3(111) system, followed by a comparative overview and perspective of recent results for topological semimetal and insulator surfaces. Moreover, we shortly discuss the perspectives of calculating helium-surface interaction potentials from ab initio calculations. Our perspective demonstrates that atom-surface scattering provides direct experimental information about the atom-surface interaction in the weak physisorption regime and can also be used to determine the lifetime and mean free path of the trapped atom. We further discuss the effects of elastic and inelastic scattering on the linewidth and lifetime of the trapped He atom with an outlook on future developments and applications.
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Affiliation(s)
- Anton Tamtögl
- Institute of Experimental Physics, Graz University of Technology, 8010 Graz, Austria.
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7
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Debiossac M, Pan P, Roncin P. Grazing incidence fast atom diffraction, similarities and differences with thermal energy atom scattering (TEAS). Phys Chem Chem Phys 2021; 23:7615-7636. [PMID: 33404037 DOI: 10.1039/d0cp05476c] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Grazing incidence fast atom diffraction (GIFAD) at surfaces has made rapid progress and has established itself as a surface analysis tool where effective energy E⊥ of the motion towards the surface is in the same range as that in thermal energy atom scattering (TEAS). To better compare the properties of both techniques, we use the diffraction patterns of helium and neon atoms impinging on a LiF (001) surface as a model system. E-Scan, θ-scan, and φ-scan are presented where the primary beam energy E is varied between a few hundred eV up to five keV, the angle of incidence θi between 0.2 and 2° and the azimuthal angle φi around 360°. The resulting diffraction charts are analyzed in terms of high and low values of effective energy E⊥. The former provides high resolution at the positions of the surface atoms and the attached repulsive interaction potentials while the second is sensitive to the attractive forces towards the surface. The recent progress of inelastic diffraction is briefly presented.
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Affiliation(s)
- Maxime Debiossac
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay (ISMO), 91405 Orsay, France.
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8
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Bocan GA, Breiss H, Szilasi S, Momeni A, Casagrande EMS, Gravielle MS, Sánchez EA, Khemliche H. Anomalous KCl(001) Surface Corrugation from Fast He Diffraction at Very Grazing Incidence. PHYSICAL REVIEW LETTERS 2020; 125:096101. [PMID: 32915632 DOI: 10.1103/physrevlett.125.096101] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 07/31/2020] [Indexed: 06/11/2023]
Abstract
We present theoretical and experimental evidence of an anomalous surface corrugation behavior in He-KCl(001) for incidence along ⟨110⟩. When the He normal energy decreases below 100 meV, i.e., He-surface distances Z>2 Å, the corrugation unexpectedly increases up to an impressive ≳85%. This is not due to van der Waals interactions but to the combination of soft potential effects and the evolution of He-cation and He-anion interactions with Z. This feature, not previously analyzed on alkali-halide surfaces, may favor the alignment properties of weakly interacting overlayers.
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Affiliation(s)
- G A Bocan
- Instituto de Nanociencia y Nanotecnología, Nodo Bariloche (CONICET-CNEA) and Instituto Balseiro (U. N. Cuyo), Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Argentina
| | - H Breiss
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - S Szilasi
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - A Momeni
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
- CY Cergy Paris Université, F-95000 Cergy, France
| | - E M Staicu Casagrande
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
| | - M S Gravielle
- Instituto de Astronomía y Física del Espacio (UBA-CONICET), Casilla de Correo 67, Sucursal 28, C1428EGA Buenos Aires, Argentina
| | - E A Sánchez
- Instituto de Nanociencia y Nanotecnología, Nodo Bariloche (CONICET-CNEA) and Instituto Balseiro (U. N. Cuyo), Centro Atómico Bariloche, Avenida Bustillo 9500, 8400 San Carlos de Bariloche, Argentina
| | - H Khemliche
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, 91405 Orsay, France
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9
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Debiossac M, Roncin P, Borisov AG. Refraction of Fast Ne Atoms in the Attractive Well of a LiF(001) Surface. J Phys Chem Lett 2020; 11:4564-4569. [PMID: 32421332 DOI: 10.1021/acs.jpclett.0c01157] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ne atoms with energies of ≤3 keV are diffracted under grazing angles of incidence from a LiF(001) surface. For a small momentum component of the incident beam perpendicular to the surface, we observe an increase in the elastic rainbow angle together with a broadening of the inelastic scattering profile. We interpret these two effects as the refraction of the atomic wave in the attractive part of the surface potential. We use a fast, rigorous dynamical diffraction calculation to find a projectile-surface potential model that enables a quantitative reproduction of the experimental data for ≤10 diffraction orders. This allows us to extract an attractive potential well depth of 10.4 meV. Our results set a benchmark for more refined surface potential models that include the weak van der Waals region, a long-standing challenge in the study of atom-surface interactions.
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Affiliation(s)
- M Debiossac
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, bât. 520, 91405 Orsay, France
| | - P Roncin
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, bât. 520, 91405 Orsay, France
| | - A G Borisov
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, bât. 520, 91405 Orsay, France
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10
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Ruckhofer A, Tamtögl A, Pusterhofer M, Bremholm M, Ernst WE. Helium-Surface Interaction and Electronic Corrugation of Bi 2Se 3(111). THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:17829-17841. [PMID: 31608131 PMCID: PMC6781485 DOI: 10.1021/acs.jpcc.9b03450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/13/2019] [Indexed: 06/10/2023]
Abstract
We present a study of the atom-surface interaction potential for the He-Bi2Se3(111) system. Using selective adsorption resonances, we are able to obtain the complete experimental band structure of atoms in the corrugated surface potential of the topological insulator Bi2Se3. He atom scattering spectra show several selective adsorption resonance features that are analyzed, starting with the free-atom approximation and a laterally averaged atom-surface interaction potential. Based on quantum mechanical calculations of the He-surface scattering intensities and resonance processes, we are then considering the three-dimensional atom-surface interaction potential, which is further refined to reproduce the experimental data. Following this analysis, the He-Bi2Se3(111) interaction potential is best represented by a corrugated Morse potential with a well depth of D = (6.54 ± 0.05) meV, a stiffness of κ = (0.58 ± 0.02) Å-1, and a surface electronic corrugation of (5.8 ± 0.2)% of the lattice constant. The experimental data may also be used as a challenging benchmark system to analyze the suitability of several van der Waals approaches: the He-Bi2Se3(111) interaction captures the fundamentals of weak adsorption systems where the binding is governed by long-range electronic correlations.
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Affiliation(s)
- Adrian Ruckhofer
- Institute
of Experimental Physics, Graz University
of Technology, Graz 8010, Austria
| | - Anton Tamtögl
- Institute
of Experimental Physics, Graz University
of Technology, Graz 8010, Austria
| | - Michael Pusterhofer
- Institute
of Experimental Physics, Graz University
of Technology, Graz 8010, Austria
| | - Martin Bremholm
- Centre
for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Aarhus 8000, Denmark
| | - Wolfgang E. Ernst
- Institute
of Experimental Physics, Graz University
of Technology, Graz 8010, Austria
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11
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Whittaker KA, Keaveney J, Hughes IG, Sargsyan A, Sarkisyan D, Adams CS. Optical response of gas-phase atoms at less than λ/80 from a dielectric surface. PHYSICAL REVIEW LETTERS 2014; 112:253201. [PMID: 25014812 DOI: 10.1103/physrevlett.112.253201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Indexed: 06/03/2023]
Abstract
We present experimental observations of atom-light interactions within tens of nanometers (down to 11 nm) of a sapphire surface. Using photon counting we detect the fluorescence from of order one thousand Rb or Cs atoms, confined in a vapor with thickness much less than the optical excitation wavelength. The asymmetry in the spectral line shape provides a direct readout of the atom-surface potential. A numerical fit indicates a power law -C(α)/r(α) with α = 3.02 ± 0.06 confirming that the van der Waals interaction dominates over other effects. The extreme sensitivity of our photon-counting technique may allow the search for atom-surface bound states.
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Affiliation(s)
- K A Whittaker
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - J Keaveney
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - I G Hughes
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - A Sargsyan
- Institute for Physical Research, National Academy of Sciences, Ashtarak 2, 0203, Armenia
| | - D Sarkisyan
- Institute for Physical Research, National Academy of Sciences, Ashtarak 2, 0203, Armenia
| | - C S Adams
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Physics, Durham University, South Road, Durham DH1 3LE, United Kingdom
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