The study of surface phonon dispersion curves is motivated by the quest for a detailed understanding forces between atoms at and in bulk. In case graphene, additional motivation comes from fact that thermal conductivity dominated contributions acoustic phonons, while optical properties are essential to understand Raman spectra. this article, we review recent progress made experimental determination graphene grown on several single-crystal metal surfaces. two main techniques usually employed...

Abstract We have determined the electron–phonon interaction in type II Dirac semimetallic 1T-PdTe 2 by means of helium atom scattering. While is isostructural with 1T-PtTe , only former superconductor. The difference can be traced to substantially larger value coupling λ = 0.58, obtained from Debye-Waller attenuation He specular peak. With this and surface Debye temperature, Θ D 106.2 K, we figured out superconducting critical T c 1.83 K given BCS theory, which good agreement (1.95 ± 0.03)...

We report an extensive structural characterization of the surface 1T-PtTe2 crystals by means helium atom scattering (HAS) and ultra-high resolution scanning tunnelling microscopy (STM). HAS reveals that this bi-dimensional presents a large corrugation (∼) in direction. The lattice constant PtTe2 derived from positions diffraction peaks up to fifth order was found be , agreement with STM x-ray measurements. This value remains unchanged temperature range between 90 580 K. These findings...

Inelastic helium atom scattering (HAS) is suitable to determine low-energy (few meV) vibrations spatially localized on structures in the nanometer range. This illustrated for nanodomes that appear often graphene (Gr) epitaxially grown single crystal metal surfaces. The nature of inelastic losses observed Gr/Ru(0001) and Gr/Cu/Ru(0001) has been clarified by intercalation Cu below Gr monolayer, which decouples layer from Ru substrate changes substantially out-of-plane, flexural phonon...

Tin diselenide (SnSe2) is a van der Waals semiconductor, which spontaneously forms subnanometric SnO2 skin once exposed to air. Here, by means of surface-science spectroscopies and density functional theory, we have investigated the charge redistribution at SnO2–SnSe2 heterojunction in both oxidative humid environments. Explicitly, find that work function pristine SnSe2 surface increases 0.23 0.40 eV upon exposure O2 air, respectively, with transfer reaching 0.56 e–/SnO2 between underlying...

The interplay between substrate interactions and electron-phonon coupling in two-dimensional (2D) materials presents a significant challenge understanding controlling their electronic properties. Here, we present comparative study of the structural characteristics, phonon dynamics, bulk monolayer NbSe$_2$ on epitaxial bilayer graphene (BLG) using helium atom scattering (HAS). High-resolution diffraction reveals (9x9)0$^{\circ}$ superstructure within monolayer, commensurate with BLG lattice,...

The interplay between substrate interactions and electron–phonon coupling in two-dimensional (2D) materials presents a significant challenge understanding controlling their electronic properties. Here, we present comparative study of the structural characteristics, phonon dynamics, bulk monolayer NbSe2 on epitaxial bilayer graphene (BLG) using helium atom scattering (HAS). High-resolution diffraction reveals (9 × 9)0° superstructure within monolayer, commensurate with BLG lattice, while...

We report a new method to produce high-quality, transparent graphene/sapphire samples, using Cu as catalyst.

We have studied the (0001) surface of 2H-MoS2 by means helium-atom scattering (HAS). The electron–phonon coupling constant, λ, this system has been determined measuring thermal attenuation specular peak at temperatures between 100 and 500 K. HAS diffraction also reveals a 3% planar dilation layer, whereas step interference measured low incidence energy indicates slight contraction layer thickness. By employing recently developed quantum-theoretical approach applied to case layered degenerate...

We present angle- and energy-resolved analysis of Ne scattering from a Ni(111) surface at moderate beam energy temperature. Variation the temperature allows transition pure quantum regime, where single-phonon events are observed, to classical multiphonon excitations observed. The latter can be reproduced by calculations. Therefore, our data lie on border between coherent regime incoherent regime.

We report helium diffraction from natural MoS2 single crystal. The high quality of the samples studied lead to appearance sharp and intense in-plane out-of-plane peaks, with unusually low background. pronounced features observed confirm corrugation 2D surface unit cell. observation along two main symmetry directions allows determining lattice constant accuracy. measured is Å. Within experimental error, parameter was found remain in temperature range between 90 522 K, good agreement...

The development of novel reflective optical elements is essential to improve the focusing neutral atomic beams. recent availability commercial thin crystals led a renewed interest in curved mirrors as for He microscopy. We have investigated reflectivity incoming atoms Cu(111), Ni(111), and Ru(0001) thickness between 50 150 $\ensuremath{\mu}\mathrm{m}$. results been compared with ones obtained from bulk crystal surfaces. Our study reveals that 100 $\ensuremath{\mu}\mathrm{m}$ thick Cu(111)...

Diffraction with matter waves has been reported since the beginning of quantum mechanics. In free space, diffraction effects have observed even objects as large C60 molecules. However, in scattering from a solid surface, pure elastic features never molecules larger than D2. Here we report observation molecular for CH4 scattered off an Ir(111) surface. These results prove that coherence is preserved, despite small separation between rotational levels and interaction surface phonons. Density...

Using a reactive molecular beam with high kinetic energy ( E kin ), it is possible to speed gas–surface reactions involving activation barriers act which would require elevated pressures if random gas used.

We have measured high-resolution angular distributions of methane scattered from a Ni(111) surface at incident energies between 68.9 meV and 108.6 meV. A sharp intense specular peak has been observed, in addition to features corresponding rotationally inelastic diffraction (RID) peaks along the two main symmetry directions Ni(111). The intensity most RID is ca. 50% one. observation sharp, coherent elastic such low suggests that single scattering dominates over trapping these energies, depth...

We show that neutral atom scattering is suitable to determine the coupling strength between a two-dimensional (2D) material and underlying substrate. This information can be obtained from thermal attenuation of specular intensity, as well angular distributions He Ne atoms in low incident energy (∼50 meV) regime. For graphene (Gr) grown on several metal substrates, there direct correlation slope measurements Gr–substrate surface phonons measurements. In addition, presents broad, classical...

We report Ne atom scattering from clean Ru(0001) and covered with a single layer of graphene. For both systems, the quantum classical regimes are observed analyzed. The to boundary is explored by varying surface temperature incident kinetic energy. smooth model used perform theoretical simulations in order reproduce angular distributions regime determine effective mass hence allow determination Debye temperature. calculations, agreement experiments, predict that subspecular at low energies...

Abstract Closed-shell atoms scattered from a metal surface exchange energy and momentum with phonons mostly via the interposed valence electrons, i.e., creation of virtual electron-hole pairs. The latter can then decay into electron-phonon interaction, as well acoustic plasmons (ASPs). While first channel is basis current inelastic atom scattering (IAS) surface-phonon spectroscopy, no attempt to observe ASPs IAS has been made so far. In this study we provide evidence ASP in Ni(111) both Ne...

The ability of the different approaches proposed to date include effects van der Waals (vdW) dispersion forces in density functional theory (DFT) is currently under debate. Here, we used diffraction He on a Ru(0 0 1) surface as challenging benchmark system analyze suitability several representative approaches, from ones correcting exchange-correlation generalized gradient approximation (GGA) functional, DFT energies through pairwise-based methods. To perform our analysis, have built seven...

The fabrication of atomically smooth metal films on supporting oxides is a quite demanding task, since most physical vapor deposition methods used metals do not work properly oxide substrates. Here, we report an alternative procedure, based performing laser polishing fused silica substrate before depositing the metallic thin film. This reduces RMS surface roughness by ca. 33%, and increases maximum grain size film from 200 nm to 1200 nm. method has been applied parabolic lens, which coated...

We present an experimental study of the initial dissociative sticking probability H2 on Pd–Cu(111) surface alloy at Pd coverages between 1–10%. The measurements have been performed using a supersonic molecular beam with incident energy range Ei = 75–163 meV. In agreement recent STM study, our results confirm that small amounts atoms significantly increase reactivity inert Cu(111) surface, although measured values were found to be much lower than ones estimated from work. For coverage 1% and...