  The Zeeman effect is an important topic in atomic spectroscopy. The induced
change in transition frequencies and amplitudes finds applications in the
Earth-field-range magnetometry. At intermediate magnetic field amplitude $B\sim
B_0 = A_\text{hfs}/\mu_B$, where $A_\text{hfs}$ is the magnetic dipole constant
of the ground state, and $\mu_B$ is the Bohr magneton ($B_0\approx 1.7$ kG for
Cs), the rigorous rule $\Delta F = 0, \pm1$ is affected by the coupling between
magnetic sub-levels induced by the field. Transitions satisfying $\Delta F =
\pm2$, referred to as magnetically-induced transitions, can be observed. Here,
we show that a significant redistribution of the Cs $6\text{S}_{1/2}\rightarrow
6\text{P}_{3/2}$ magnetically-induced transition intensities occurs with
increasing magnetic field. We observe that the strongest transition in the
group $F_g=3\rightarrow F_e=5$ ($\sigma^+$ polarization) for $B<B_0$ cease to
be the strongest for $B>3 B_0$. On the other hand, the strongest transition in
the group $F_g=2\rightarrow F_e=4$ ($\sigma^-$ polarization) remains so for all
our measurements with magnetic fields up to 9 kG. These results are in
agreement with a theoretical model. The model predicts that similar
observations can be made for all alkali metals, including Na, K and Rb atoms.
Our findings are important for magnetometers utilizing the Zeeman effect above
Earth field, following the rapid development of micro-machined vapor-cell-based
sensors.

Atomic Physics