Disorientation of 3He 1D states in 3He-3He collisions

Cross sections have been measured for the disorientation of the 3 1D, 4 1D, and 5 1D states of 3He in collisions with the ground state atoms. Oriented n1D state atoms are produced by exciting in a discharge 3He atoms whose nuclei have been oriented by optical pumping. The role of hyperfine coupling is investigated and the theoretical treatment of the effect of collisions on the orientation of the excited atom, which does not require instantaneous recoupling of the nuclear spin I and the electronic angular momentum J after each collision, is presented.