Abstract
We have studied the effect of resonant electronic-state coupling on the formation of ultracold ground-state . Ultracold molecules are formed by photoassociation (PA) to a coupled pair of states, and , in the region below the limit. Subsequent radiative decay produces high vibrational levels of the ground state, . The population distribution of these -state vibrational levels is monitored by resonance-enhanced two-photon ionization through the state. We find that the populations of vibrational levels are far larger than can be accounted for by the Franck-Condon factors for transitions with the state treated as a single channel. Further, the ground-state molecule population exhibits oscillatory behavior as the PA laser is tuned through a succession of state vibrational levels. Both of these effects are explained by a calculation of transition amplitudes that includes the resonant character of the spin-orbit coupling of the two states. The resulting enhancement of more deeply bound ground-state molecule formation will be useful for future experiments on ultracold molecules.
- Received 4 June 2007
DOI:https://doi.org/10.1103/PhysRevA.76.022504
©2007 American Physical Society