• molecular beams;
  • epitaxy;
  • quantum effects;
  • scanning tunneling microscopy;
  • surface structure
Thumbnail image of graphical abstract

“The smoothest surface ever made”, that is, a mirror for atoms comprising a Pb thin film on Si(111), is stabilized through quantum size effects to be atomically flat. It shows an absolute reflectivity for He atoms of 15%, and we report on how values close to 40% could be obtained. This highly reflective mirror can also be electrostatically bent to focus the He beam into a sub-micrometer spot. This implies that current prototype scanning helium atom microscopy/diffractometry instruments could easily reach nanometer resolution.