A thermal energy molecular beam source for use in scattering experiments

Abstract

A new nozzle source is discussed that produces a high-intensity molecular beam with very small dispersion in velocity. When signal-to-noise ratio in scattered beam experiments is used as a measure of performance this source is shown to be approximately equal in quality to a Kantrowitz-Grey source of comparable size. Furthermore it is argued that many existing Kantrowitz-Grey sources could be operated as simple nozzle sources with no appreciable loss in performance. The present source has several new features. The beam intensity is uniform over the beam cross section. Source performance is not strongly dependent on skimmer geometry; hence, a simple collimating hole in a plate suffices. Source performance is quite insensitive to the size of the collimating hole and its distance from the nozzle; thus, they may be adjusted to tailor the size and shape of the beam to the particular application. The present source may be uniquely suitable for a proposed new method of beam collimation.

Micrometer-sized nozzles and skimmers for the production of supersonic He atom beams

“…Similar glass nozzles have been used frequently in the past, but apparently with openings typically 20 m or larger. 18 The present nozzles were drawn from thick-walled ͓4 mm outside diameter ͑o.d.͒ 0.6 mm i.d.͔. Duran Glass high-pressure capillaries, in this case until the inner channel closed completely.…”

Microscopic fused silica capillary nozzles as supersonic molecular beam sources

“…The use of glass tubing to fabricate supersonic molecular beam nozzles dates to at least Moran's beam experiments in 1968 [11,12]. Moran's nozzles, roughly 20 µm diameter, were formed by drawing and then fire-polishing the soft glass tubing.…”