Two-Photon Optical Pumping and Optical Pumping of Alkali - Noble Gas Excimers.

We report the first successful attempt to spin polarize the ground state of an atom with highly off-resonant light (detuned by as much as 100 (ANGSTROM) from an atomic resonance line). We believe this to be mediated by molecular transitions within the short-lived alkalinoble gas excimer molecules, and we discuss the implications this has on the magnetic quantum numbers and coupling schemes in these molecules. We also report the first evidence of atomic ground -state spin polarization by multi-photon excitation. More specifically, a slight peak in polarization above the excimer background mentioned above has been observed in Rubidium vapour excited by a single laser tuned to the two-photon, non-stepwise, transition 5S(,1/2)(--->)(, )5P(,3/2)(-- ->)(, )5D.(,). We present the first direct study of the fate of nuclear spin in the excited state (perturbed by foreign gases at high pressure) by looking at how it affects the electronic spin polarization of Rubidium pumped by elliptically polarized D(,1) light.