Laser optical pumping of atomic beams
Hammond, Mark Stuart
Dunning, F. Barry
Master of Arts
Beams of heavy rare gas metastable atoms with a high degree of polarization have been produced by optical pumping using a variety of dye laser systems. Argon (Pa) metastable atoms were efficiently polarized. but frequency instabilities in the output of the simple, multimode Ozazine 75 dye laser used prevented stable, long-term polarizations from being achieved. Stable optical pumping of a Ne (P3) beam was achieved using a similar DCM dye laser. Frequency jitter due to low dye viscosity essentially broadened the narrow spectral components of the laser lineshape. allowing a large degree of polarization to be obtained for long periods of time. In order to insure controllable and reliable performance in the optical pumping of rare gas metastable atom beams, a frequency modulation technique has been developed. By creating sidebands between laser cavity modes. frequency modulation creates a broad qua si-continuous frequency spectrum. The negative effects of frequency drifts are thus eliminated by spreading radiation across the overall laser linewidth. A frequency modulated LD 7 dye laser was used to successfully polarize an argon metastable atom beam. High polarizations were routinely obtained for periods of several hours. The technique is suitable for use in optically pumping a wide variety of atomic species for the study of electron spin and orbital orientation dependencies in many collision processes.