Vanishing electric dipole transition moment
Abstract
We have discovered an interference which results in the vanishing of some electric dipole transition amplitudes. A transitionmatrix element T between certain S and P sublevels with the same value of M_{F} vanishes when an applied magnetic field satisfies X_{s}+X_{p}=2M_{F}, where X=μ_{B}g_{J}BA, and A is the hfs constant. There must be an avoided crossing between the two states of the same M_{F} which can only occur when one of the hyperfine manifolds has an inverted Zeeman effect. These conditions imply M_{F}<0 and I>J. We observed the vanishing of T in ^{23}Na for one of the ΔM_{F}=0 optical transitions of the 3S_{12}(F=1)>3P_{12}(F=1) manifold. Absorption of cw laser light was monitored by observing total fluorescence perpendicular to both the atomic and laser beams, and absorption vanished near an applied field of 155 G. T vanishes for a large number of cases including rf and microwave frequencies and is a rather general consequence of angular momentum selection rules and perturbation theory. This phenomenon may have application in optical pumping, Lambshift measurements, and atomic weak neutralcurrent experiments.
 Publication:

Physical Review A
 Pub Date:
 February 1979
 DOI:
 10.1103/PhysRevA.19.700
 Bibcode:
 1979PhRvA..19..700D