Physics of Optically Pumped Alkali-Metal Atoms

Abstract

Abstract : Work supported by this grant led to major theoretical and experimental advances in the physics of sodium (Na) guide stars for use in adaptive optics. We developed a powerful and realistic new theory of the effect of velocity-changing and spin changing collisions on optically pumped atoms at low pressures, similar to those of Na guide star atoms at altitude of about 100 km in the earth's atmosphere. Particularly useful was the development of new cusp kernels to describe the combined effects of strong velocity changing collisions acting simultaneously with spin precession in geomagnetic fields and spin-exchange collisions with oxygen molecules and dissociated oxygen atoms in the upper atmosphere. We implemented laboratory experiments that mimicked as closely as possible the collisional conditions of the upper atmosphere, given the unavoidable need for constraining cell walls. We developed a new, temperature-insensitive way to use Faraday rotation to lock a tunable diode laser to an arbitrary frequency in the absorption spectrum of an atomic resonance line.