The break-down of hyperfine structure coupling induced by the Zeeman effect on aluminum 2S1/2→2P1/2 transition, measured by tunable diode-laser induced fluorescence

This study highlights the diode laser-based measurements of the aluminum transition S-2(1/2) -> P-2(1/2) at 394.401 nm, which is affected by hyperfine structure splitting caused by nuclear-spin coupling and by the Zeeman effect. If the external magnetic field is strong enough, the nuclear-spin IJ coupling breaks down, whereas the Zeeman splitting continues to be ruled by the JS coupling. The diode laser-based measurements show this departure from aluminum transition IJ coupling for magnetic fields higher than 0.1 T. In this case, the line profile is affected by Doppler broadening and a large Zeeman splitting (higher than Doppler FWHM) and it can be solved by tunable diode-laser induced fluorescence measurements. The theoretical Zeeman splitting ruled by the JS coupling at high magnetic fields (0.1-0.4 T) was successfully verified while comparing the magnetic field, measured by Zeeman splitting and the Hall probe in the same elementary volume. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3579446]