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

By experimental exploration of the so-called lambda-Zeeman technique based on Rb nano-cell use we reveal for the first time a strong modification of the probabilities of Rb-87 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 pi-polarized exciting diode laser radiation (lambda = 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.