Zeeman molecular probe for tests of fundamental physical constants

The impact of the Zeeman effect on the A-doublet spectra of diatomic radicals is analysed from the point of view of a possible cosmological variation of the proton-to-electron mass ratio, mu The actual model calculations performed for the (2)Pi(3/2) and (2)Pi(1/2) states of (OH)-O-16 reveal that the Lambda-doublet energy levels of diatomic radicals can be tuned to degeneracy by means of the Zeeman effect using realistic magnetic fields. Tuning this degeneracy allows for a dramatic enhancement of the relative mass sensitivity coefficients of the corresponding transitions and for a substantial reduction of their Doppler broadening. Moreover, unlike their field-free counterparts associated with the degeneracies arising due to the A similar to 48 situations (A and B being the spin-orbit and rotation constant, respectively), the electric dipole allowed e <-> f Zeeman-tuned transitions exhibit favourable intensities, thus evidencing their promising potential.