Rovibrational energy levels of the LiOLi molecule from dispersed fluorescence and stimulated emission pumping studies

Dispersed fluorescence (DF) and stimulated emission pumping (SEP) experiments have been carried out on the jet-cooled (LiOLi)-Li-7-O-16-Li-7 molecule. Rotationally resolved SEP bands to v(2)(l)(l=0,2) vibrational angular momentum levels show that LiOLi is a linear molecule. The DF experiments have resulted in the measurement of 54 (v(1),v(2)(l),0) levels of the X (1)Sigma(g)(+) ground state, up to 6000 cm(-1). The energy levels determined experimentally are amazingly close to those calculated very recently for a high-level ab initio LiOLi(X (1)Sigma(g)(+)) potential surface. The DF vibrational level energies are analyzed and discussed in terms of a global fit to an 11-term power series. From the SEP experiments, effective rotational constants B-v1,v(2)(l),0 for several of these vibrational levels [including sigma(g)(+)(l=0) and delta(g)(l=2) vibrational angular momentum states for (v(1),v(2)(l)greater than or equal to2(even),v(3)=0) levels] have also been determined. The bond distance R-0 is estimated to be 1.611+/-0.003 A from an extrapolation of B-v1,0,0 values. Finally, the unusual "Li+O-2Li+" ionic bonding and the low omega(2)=112 cm(-1) bending frequency for LiOLi(X (1)Sigma(g)(+)) are briefly discussed. (C) 2002 American Institute of Physics.