title: Forbidden transitions in a magneto-optical trap.
abstract: We report the first observation of a nondipole transition in an ultracold atomic vapor. We excite the 3P-4P electric quadrupole (E2) transition in 23Na confined in a magneto-optical trap, and we demonstrate its application to high-resolution spectroscopy by making the first measurement of the hyperfine structure of the 4P(1/2) level and extracting the magnetic dipole constant A=30.6+/-0.1 MHz. We use cw optical-optical double resonance accompanied by photoionization to probe the transition.
authors.affiliation: Department of Physics and Astronomy and Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14627, USA.
authors.forename: M
authors.initials: M
authors.lastname: Bhattacharya
authors.forename: C
authors.initials: C
authors.lastname: Haimberger
authors.forename: N P
authors.initials: NP
authors.lastname: Bigelow