QUANTITATIVE SPECTROSCOPY OF Rb ATOMS IN STRONG MAGNETIC FIELD BASED ON SUBMICRON THIN VAPOUR.
Résumé
The energy levels of atoms placed in an external magnetic field undergo frequency shifts and changes in their transition probabilities. It is demonstrated that using fluorescence spectra from a submicron thin vapour cell (STC) with the thickness L = λ/2, it is possible to efficiently study the above mentioned changes (“half-λ Zeeman technique” (HLZT)). The circularly polarized beam of extended-cavity diode laser (λ = 794 nm, laser bandwidth γL < 1 MHz) resonant with 87Rb D1 transition, after passing through Faraday isolator is directed onto the Rb STC with the thickness L = λ/2. The temperature of the STC is 120 °C, corresponding to N ~ 1013 atom/cm3. STC was provided by a special oven with 3 openings: 2 inlets for laser beam passage, and one orthogonal inlet for side fluorescence detection. This geometry allows simultaneous recording of fluorescence and transmission spectra. STC with the oven is placed between two strong permanent ring magnets and by changing the distance between them it is possible to form a strong magnetic field up to 4500 G. In [1], “λ-Zeeman technique” (LZT) is shown to be efficient to study individual transitions between the Zeeman sublevels of hyperfine levels in an external magnetic field up to 2400 G. LZT uses STC with thickness L = λ, where λ is 794 nm (780 nm) for D1 line (D2 line) of Rb. Narrow velocity selective optical pumping/saturation (VSOP) resonances in the transmission spectrum of the STC are split into several components in the magnetic field; their frequency positions and probabilities depend on the B-field. We present comparison of HLZT and LZT in a wide region of magnetic fields up to 4500 G. We present the fluorescence spectrum for L = λ/2 and the transmission spectrum for L = λ. The VSOP resonances in the LZT-curve are narrower meanwhile the advantage of HLZT is that the fluorescence appears on a flat background. Applications such as magnetometer with high spatial resolution and the theoretical model describing well the experiment will be presented.