Atom diffraction with a ‘natural’ metastable atom nozzle beam
J.‐C. Karam, N Wipf, Jules Grucker +7 more
The resonant metastability-exchange process is used to obtain a metastable atom beam with intrinsic properties close to those of a ground-state atom nozzle beam (small angular aperture, narrow velocity distribution). The estimated effective source diameter (15 µm) is small enough to provide at a distance of 597 mm a transverse coherence radius of about 873 nm for argon, 1236 nm for neon and 1660 nm for helium. It is demonstrated both by experiment and numerical calculations with He*, Ne* and Ar* metastable atoms, that this beam gives rise to diffraction effects on the transmitted angular pattern of a silicon-nitride nano-slit grating (period 100 nm). Observed patterns are in good agreement with previous measurements with He* and Ne* metastable atoms. For argon, a calculation taking into account the angular aperture of the beam (0.35 mrad) and the effect of the van der Waals interaction—the van der Waals constant C 3 = 1.83 +0.1 −0.15 au being derived from spectroscopic data—leads to a good agreement with experiment.
Journal of Physics B Atomic Molecular and Optical Physics•Jul 18, 2005•21 citations