  We describe the so-called "Lambda-Zeeman method" to investigate individual
hyperfine transitions between Zeeman sublevels of atoms in an external magnetic
field of 0.1 mT - 0.25 T. Atoms are confined in a nanocell with thickness L =
Lambda, where Lambda is the resonant wavelength (794 nm or 780 nm for D1 or D2
line of Rb). Narrow resonances in the transmission spectrum of the nanocell are
split into several components in a magnetic field; their frequency positions
and probabilities depend on the B-field. Possible applications are described,
such as magnetometers with nanometric spatial resolution and tunable atomic
frequency references.
