Spectroscopy of low-energy atoms released from a solid noble-gas matrix: Proposal for a trap-loading technique

Abstract

We have studied the velocity distribution of chromium atoms released from a solid neon matrix at cryogenic temperatures via Doppler spectroscopy. The Ne matrix is grown by directing a small flux of gas onto a cold substrate, while Cr atoms are simultaneously implanted by laser ablation, with the resultant plume directed toward the growing matrix. The atoms are then released by a heat pulse. We have observed neutral Cr atoms at temperatures around $13\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ with densities close to ${10}^{12}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. The released atoms have a large initial drift velocity, explained by simple kinetic theory arguments, due to the light species' drag force. The scheme could be adapted to produce cryogenic beams of atoms, molecules, and possibly ions, for collisional studies and spectroscopy. However, our main motivation was the construction of a hydrogen trap, and here we discuss the prospects and problems of using this technique for this purpose.