Autler-Townes effect in a sodium molecular-ladder scheme
- Department of Physics, University of Kaiserslautern, Erwin-Schroedinger Strasse, D-67663 Kaiserslautern (Germany)
We report results from studies of the Autler-Townes (AT) effect observed in sodium molecules from a molecular beam. A relatively weak laser field P couples an initially populated rovibronic level g in the electronic ground state (here X {sup 1}{sigma}{sub g}{sup +},v{sup ''}=0, J{sup ''}=7) to a selected excited rovibronic level e (here A {sup 1}{sigma}{sub u}{sup +},v{sup '}=10, J{sup '}=8), which in turn is coupled by a relatively strong laser field S to a more highly excited level f (here 5 {sup 1}{sigma}{sub g}{sup +},v=10, J=9), a scheme we idealize as a three-state ladder. The AT effect is seen by scanning the frequency of the P field while recording fluorescence from both the e and f levels in separate detection channels. We present qualitative theoretical considerations showing that, when the P field is weak, the ratio of doublet component areas in the excitation spectrum from level f can be used to determine the lifetime of this level. We obtain a value of 17{+-}3 ns. When the P field is stronger, such that its Rabi frequency is larger than the decay rate of level e, the fraction of f-level population that decays to the intermediate electronic state A {sup 1}{sigma}{sub u}{sup +} can be deduced from the AT spectrum. When supplemented with values of Franck-Condon and Hoenl-London factors, our measurements give a value for the branching ratio (the fraction returning to level e) of r{sub e}=0.145 with a statistical error of {+-}0.004. The use of a strong P field on the g-e transition and a weak S field as a probe on the e-f transition results in complex line shapes in the excitation spectrum of level f, not showing the familiar Autler-Townes doublet structure.
- OSTI ID:
- 20650097
- Journal Information:
- Physical Review. A, Vol. 71, Issue 2; Other Information: DOI: 10.1103/PhysRevA.71.023401; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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