Diffraction of helium and hydrogen atoms through single-layer graphene.

Diffraction of atoms from surfaces provides detailed insights into structures, interactions, and dynamical processes. However, the method is currently limited to measurements in reflection—diffraction through materials has only been demonstrated for subatomic particles and is an outstanding challenge for atoms. In this work, we diffract helium and hydrogen atoms at kilo–electron volt energies through single-layer graphene at normal incidence. Despite the atoms' high kinetic energy as well as coupling to the electronic system of graphene, we observe coherent scattering. This preservation of coherence was the result of the limited momentum transfer between the projectile and the lattice, resulting from interaction times on the femtosecond scale. Editor's summary: High-energy hydrogen and helium atoms have been shown to diffract through graphene without damaging its lattice. Kanitz et al. were able to observe diffraction with atoms having kinetic energies normal to the lattice of up to 1.6 kilo–electron volts despite the expected detrimental effects of decoherence and lattice damage (see the Perspective by Holst). Unlike electron diffraction, this method could enable studies of diffraction of matter waves prepared in specific internal states in transmission experiments. —Phil Szuromi [ABSTRACT FROM AUTHOR]