Fast hydrogen atom diffraction through monocrystalline graphene

Abstract

We report fast atom diffraction through single-layer graphene using hydrogen atoms at kinetic energies from 150 to 1200 eV. High-resolution images reveal overlapping hexagonal patterns from coexisting monocrystalline domains. Time-of-flight tagging confirms negligible energy loss, making the method suitable for matter-wave interferometry. The diffraction is well described by the eikonal approximation, with accurate modeling requiring the full 3D interaction potential from DFT. Simpler models fail to reproduce the data, highlighting the exceptional sensitivity of diffraction patterns to atom-surface interactions and their potential for spectroscopic applications.

Figures (5)

• Figure 1: Diffraction images recorded with H atoms impinging on single layer graphene deposited on TEM grids. All images are normalized to the first-order diffraction peak. The yield in the image center (black circle) has been further divided by 1000 to reveal the spatial distribution of ballistic trajectories through holes present in the graphene monolayer. (a) 300 eV ( Ted Pella); (b) 300 eV ( Graphenea) ; (c) determination of position and orientation of single crystalline domains ( Ted Pella) -- arrows point to the reconstructed location of the diffracting domains; (d) 600 eV ( Graphenea).
• Figure 2: Sorting of elastic and inelastic scattering events. (a) Raw picture (300 eV, Ted Pella); (b) Kinetic energy distribution of H atoms transmitted through graphene -- full line: ballistic peak, dot-dashed line: diffuse background, symbols: diffraction peaks; (c) Inelastic scattering events ($E\leq 288$ eV); (d) Elastic scattering events ($E\geq 300$ eV). The diffraction signal in (b) was obtained by subtracting the kinetic energy distribution recorded in an adjacent area of similar size. No subtraction is needed to obtain the filtered images. All images in these panels were binned to $64\times 64$ pixels to improve statistics.
• Figure 3: Schematic view of the modeling of coherent diffraction of a beam of hydrogen atoms through a sheet of graphene (see text).
• Figure 4: Hydrogen-graphene interaction potential as a function of $z$ ($z=0$ corresponds to the surface) for three positions in the $xy$ plane: at the center of the carbon ring (in blue, Center), facing a carbon atom (in red, Atom) and in the middle of a carbon-carbon bond (in orange, Bond). The different models used to generate these potentials are ab initio (solid lines), Brand et al. Brand2019 (dashed lines), H-C binary (divided by 10, dotted lines) and SCC-DFTB Ehemann2012 (dash dotted lines).
• Figure 5: Diffraction pattern of a beam of hydrogen atoms of kinetic energy $E=300$ eV through a graphene sheet. Theoretical predictions obtained using the eikonal approximation and three interaction potential models are compared with experimental measurements: (a) experiment (diffusion background subtracted), (b) ab initio, (c) H-C binary, and (d) Brand et al. Brand2019.