Study of “forbidden” atomic transitions on D2 line using Rb nano-cell placed in external magnetic field

By experimental exploration of the so-called λ -Zeeman technique based on Rb nano-cell use we reveal for the first time a strong modification of the probabilities of 87 Rb D 2 line F g = 1 → F e = 0, 1, 2, 3 atomic transitions, including “forbidden” F g = 1, m F = 0 → F e = 1, m F = 0 and F g = 1, m F = −1 → F e = 3, m F = −1 transitions (these are “forbidden” transitions when B = 0) in a strong external magnetic field B in the range of 100−1100 G. For π -polarized exciting diode laser radiation ( λ = 780 nm) these “forbidden” transitions at B > 150 G are among the strongest atomic transitions in the detected transmission spectra. The frequency shifts of the individual hyperfine transitions versus magnetic field are also presented: particularly, F g = 1, m F = +1 → F e = 1, m F = +1 atomic transition has a unique behavior, since its frequency remains practically unchanged when B varies from 100 to 1100 G. The developed theoretical model well describes the experiment.