Direct magneto-optical compression of an effusive atomic beam for high-resolution focused ion beam application

Abstract

An atomic rubidium beam formed in a 70 mm long two-dimensional magneto-optical trap (2D MOT), directly loaded from a collimated Knudsen source, is analyzed using laser-induced fluorescence. The longitudinal velocity distribution, the transverse temperature and the flux of the atomic beam are reported. The equivalent transverse reduced brightness of an ion beam with similar properties as the atomic beam is calculated because the beam is developed to be photoionized and applied in a focused ion beam. In a single two-dimensional magneto-optical trapping step an equivalent transverse reduced brightness of $(1.0\begin{array}{c}+0.8-0.4\end{array})$ $\times 10^6$ A/(m${}^2$ sr eV) was achieved with a beam flux equivalent to $(0.6\begin{array}{c}+0.3-0.2\end{array})$ nA. The temperature of the beam is further reduced with an optical molasses after the 2D MOT. This increased the equivalent brightness to $(6\begin{array}{c}+5-2\end{array})$$\times 10^6$ A/(m${}^2$ sr eV). For currents below 10 pA, for which disorder-induced heating can be suppressed, this number is also a good estimate of the ion beam brightness that can be expected. Such an ion beam brightness would be a six times improvement over the liquid metal ion source and could improve the resolution in focused ion beam nanofabrication.

arXiv comment10 pages, 8 figures, 1 table

References in corpus (7)

• Atom Interferometers
• A high-flux 2D MOT source for cold lithium atoms
• Bright focused ion beam sources based on laser-cooled atoms
• A compact high-flux source of cold sodium atoms
• Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam
• Three-dimensional laser cooling at the Doppler limit
• Performance predictions for a laser intensified thermal beam for use in high resolution Focused Ion Beam instruments

Cited by in corpus (5)

• A high repetition deterministic single ion source
• Cavity-enhanced photoionization of an ultracold rubidium beam for application in focused ion beams
• Investigation of Rb${}^{+}$ Milling Rates using an Ultracold Focused Ion Beam
• Study of Surface Damage in Silicon by Irradiation with Focused Rubidium Ions
• Selective ionization of Rydberg atoms to reduce the energy spread of a cold atom focused ion beam