ROTATIONALLY RESOLVED ABSORPTION-SPECTRUM OF THE O-2 DIMER IN THE VISIBLE RANGE

The rotationally resolved absorption spectrum of two bands of the oxyg en dimer near 630 and 578 nm have been recorded by intracavity laser a bsorption spectroscopy both in a supersonic slit expansion of pure O-2 and in a cell cooled at 77 K. These bands correspond to the transitio ns [O-2((1)Delta(g))(v=0)](2) <-- [O-2((3)Sigma(g)(-)),(v=0)](2) and [ O-2((l)Delta(g))(v=0)-O-2((1)Delta(g))(r=1)] <-- [O-2((3)Sigma(g)(-))( v=0)](2). From the extension of the highly congested rotational struct ure, the dissociation energy of the ground and excited states are esti mated to be 80 and 40 cm(-1), respectively. These values agree reasona bly well with the results of ab initio calculations of the potential e nergy surface. (C) 1998 Elsevier Science B,V. All rights reserved.