title: Breakdown of angular momentum selection rules in high pressure optical pumping experiments.
abstract: We present measurements, by using two complementary methods, of the breakdown of atomic angular momentum selection rules in He-broadened Rb vapor. Atomic dark states are rendered weakly absorbing due to fine-structure mixing during Rb-He collisions. The effect substantially increases the photon demand for optical pumping of dense vapors.
authors.affiliation: Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: B
authors.initials: B
authors.lastname: Lancor
authors.forename: E
authors.initials: E
authors.lastname: Babcock
authors.forename: R
authors.initials: R
authors.lastname: Wyllie
authors.forename: T G
authors.initials: TG
authors.lastname: Walker