Source of slow lithium atoms from Ne or H2 matrix isolation sublimation

Abstract

We have studied, via laser absorption spectroscopy, the velocity distribution of (7)Li atoms released from cryogenic matrices of solid neon or molecular hydrogen. The Li atoms are implanted into the Ne or H(2) matrices--grown onto a sapphire substrate--by laser ablation of a solid Li or LiH precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms. With a NiCr film resistor deposited directly onto the sapphire substrate we are able to transfer high instantaneous power to the matrix, thus reaching a fast sublimation regime. In this regime the Li atoms can get entrained in the released matrix gas, and we were also able to achieve matrix sublimation times down to 10 μs for both H(2) or Ne matrix, enabling us to proceed with the trapping of the species of our interest such as atomic hydrogen, lithium, and molecules. The sublimation of the H(2) matrix, with its large center-of-mass velocity, provides evidence for a new regime of one-dimensional thermalization. The laser ablated Li seems to penetrate the H(2) matrix deeper than it does in Ne.