LASER SPECTROSCOPIC STUDIES OF THE STARK STRUCTURE OF THE N=33 HYDROGEN DIAMAGNETIC MANIFOLD IN PARALLEL FIELDS

High resolution spectroscopy is performed on a highly excited diamagnetic manifold of the hydrogen atom perturbed by a weak electric field parallel to the magnetic field. A two-step excitation is realized via the 2p level, using two single-mode VUV and UV pulsed lasers. Simultaneous crossings are observed at some peculiar values of the electric field. Positions and intensities of the spectral lines are found to be in close agreement with the calculated predictions taking into account the mixing in the intermediate state.