COMPLETE G-U SYMMETRY-BREAKING IN HIGHLY EXCITED VALENCE STATES OF THE HD MOLECULE

We performed a study of rovibrational energy levels of the (H) over ba r(1)Sigma(g)(+) and (B) over bar(1)Sigma(u)(+) states in HD in a three -photon experiment involving extreme ultraviolet (XUV), visible, and u ltraviolet laser radiation. An analysis of level shifts with respect t o adiabatic energies, deduced from level energies in H-2 and D-2, show s strong non-adiabatic interaction between these two states, implying complete g-u symmetry breaking over a wide range of v and J quantum nu mbers. (C) 1998 Elsevier Science B.V. All rights reserved.