Wall interactions of spin-polarized atoms

Spin-polarized atoms have applications in many areas, including biological magnetic resonance imaging, optical magnetometry, atomic clocks, and fundamental symmetry studies. Polarized atoms are often held in a container, most commonly a glass cell. Their interactions with the walls of the container during their collisions with the walls are often the main cause of spin relaxation, which determines the ultimate attainable polarization, and frequency shift, which affects the long-term frequency stability in atomic clocks. A critical review of studies of wall interactions of spin-polarized atoms done in the past six decades is presented, including the hydrogen atom, alkali metal atoms, and diamagnetic atoms with S01 ground states such as mercury, cadmium, and noble gas atoms. The review summarizes the progress that has been made in understanding the nature of wall interactions and the physical mechanisms of spin relaxation and frequency shift due to wall collisions. It also points out those issues, particularly in connection with the widely used antirelaxation coatings, that are not yet understood.