An investigation of spin depolarization at solid surfaces using optically pumped sodium atoms

The relaxation of spin-polarized sodium atoms on selected solid surfaces is examined. Non-Boltzmann hyperfine energy level population distributions were produced in the ground state of a supersonic beam of sodium atoms using hyperfine optical pumping. The ground state distribution was probed before and after scattering from an atomically clean surface using high resolution laser induced fluorescence spectroscopy. The surfaces studied were single crystal lithium fluoride cleaved in the (100) direction, single crystal silicon cleaved in the (111) direction, and polycrystalline tungsten. Spin relaxation of the sodium valence electron back down to its thermal ground state was monitored as a function of surface temperature and adsorbate coverage with the goal of developing an understanding of the surface properties which govern the relaxation, such as the residence time of the adsorbed atom, the local surface magnetic field strength, and the diffusion rate of the adsorbed atom across the surface