We report results from studies of the Autler-Townes ͑AT͒ 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 1 ⌺ g + , vЉ =0, JЉ =7͒ to a selected excited rovibronic level e ͑here A 1 ⌺ u + , vЈ = 10, JЈ =8͒, which in turn is coupled by a relatively strong laser field S to a more highly excited level f ͑here 5 1 ⌺ g + , v = 10, J =9͒, 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 1 ⌺ u + can be deduced from the AT spectrum. When supplemented with values of Franck-Condon and Hönl-London factors, our measurements give a value for the branching ratio ͑the fraction returning to level e͒ of r 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.
For transport needs the hydrogen is mostly stored in a compressed (at 350-700 bars) form, while methods for its storage at lower pressures are rapidly developing. In particular, nanoporous oxides and zeolites, which do not normally absorb notable amount of hydrogen, with a small Pd additive or ion exchange demonstrate enhanced hydrogen adsorption properties. An original thermogravimetric method has been developed to study the hydrogen adsorption in zeolite, consisting of its heating in the inert gas (argon, nitrogen) flow and cooling in the hydrogen atmosphere. It is found that natural zeolite (clinoptilolite) with Mg-ion exchange possesses a high adsorption capacity for hydrogen -up to 6.2 wt%, which is explained by its encapsulation in zeolite pores. The FTIR spectra of the hydrogen-treated samples have shown new absorption bands at 2340 and 2360 cm -1 .
We report a study of fine-structure mixing Rb(5 2 D 5/2)→Rb(5 2 D 3/2) in collisions with ground-state Rb atoms. In the experiment, two-photon cw laser excitation was applied to the Rb vapor cell. The measured cross section for the process was (5.8Ϯ1.9)ϫ10 Ϫ14 cm 2. Theoretical calculations using nonadiabatic collision theory gave a value of 3.4ϫ10 Ϫ14 cm 2 .
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