Diffraction of Matter Waves from Nanostructures:
New Physics and Novel Applications
Recent nanotechnology advances have made it possible to produce free standing
transmission gratings with slits of 50 nm width. The diffraction of atoms, molecules
and small clusters from such gratings provide beautiful textbook examples of
matter wave phenomena [1]. Since only the wave nature of the particles is involved
even the exceedingly weakly bound He dimers (binding energy " 10-3 K (@
10-7 eV)) and other small He clusters with up to 26 atoms can be separated by
virtue of their different de Broglie wavelengths. Deviations of the diffraction
intensities from predictions by traditional optics have been used to measure
for the first time the long range particle-surface potentials [2] and the geometrical
sizes of the He dimer (" 50 A) [3] and of the trimer (10 A).
With three identical transmission gratings a Mach-Zehnder universal matter wave
interferometer has been demonstrated. This device opens up a wide range of intriguing
new experiments in molecular physics and has long range implications for studying
decoherence as predicted by modern quantum theories of gravity. Transmission
Fresnel zone plates have also been used to focus an atomic beam onto a 1 micron
diameter spot [4], so that an essential part of a uniquely surface sensitive
atom microscope is now available.
[1] W. Schöllkopf and J.P. Toennies, Science 266, 1345 (1994)
[2] R.E. Grisenti, W. Schöllkopf, J.P. Toennies, G.C. Hegerfeldt and T.
Köhler,
Phys. Rev. Lett. 83, 1755 (1999)
[3] R.E. Grisenti, W. Schöllkopf, J.P. Toennies, G.C. Hegerfeldt, T. Köhler
and M. Stoll,
Phys. Rev. Lett. 85, 2284 (2000)
[4] R.B. Doak, R.E. Grisenti, S. Rehbein, G. Schmahl, J.P. Toennies and Ch.
Wöll,
Phys. Rev. Lett. 83, 4229 (1999)