THE 3D RYDBERG STATE OF THE BEH MOLECULE

The absorption and the emission spectra of the BeH and BeD molecules in the region of 1850 angstrom are rotationally analysed. The features observed are shown to correspond to a transition between the X2-SIGMA+ ground state and a 3d molecular complex that is strongly predissociated by the C2-SIGMA+ state. Rotational constants for the v = 0 and v = 1 levels of the 3d state are derived by matrix diagonalization techniques, assuming interaction with the F(4p-sigma)2-SIGMA+ state. A tentative assignment of previously observed absorption bands to transitions involving the v = 2 level of the 3d state is given. The 2-0 band of the B2-PI-X2-SIGMA+ transition of BeH and BeD is also identified in this region. The predissociation by the C2-SIGMA+ state is discussed.