RYDBERG STATES OF THE KR2 MOLECULE

Spectra attributed to transitions from the 5ssigma a 3SIGMA(u)+ metast able state of Kr2 to excited Rydberg states have been observed by intr acavity and multipass absorption and by laser excitation spectroscopy. Four distinct Rydberg series converging on the X2SIGMA(u)+ core of Kr 2+ have been identified. Rotational structure is not resolved in any o f the observed spectra. Most of the spectra can be assigned to vibroni c transitions in the nflambda(3PI(g), 3SIGMA(g)) and nplambda(3PI(g), 3SIGMA(g)+) <-- a 3SIGMA(u)+ series by analogy with similar spectra in the lighter rare gas dimers. The 6ppi 3PI(g) <-- a 3SIGMA(u)+ and 8ps igma 3SIGMA(g) <-- a 3SIGMA(u)+ transitions observed in the approximat ely 19 200-18 200 cm-1 region exhibit many bands with v' not-equal 0 i n their (v'-v'') vibrational band system developments. The higher n va lue members of these and other observed series are dominated by (0-0) transitions. All series are perturbed in a few energy regions by state s built on the excited ion core states A 2PI3/2g and B 2PI3/2u. Laser excitation spectra for the 8psigma 3SIGMA(g)+ <-- a transition obtaine d by monitoring various 5p --> 5s emission lines of atomic krypton sug gest that the 8psigma 3SIGMA(g)+ Rydberg state of Kr2 is predissociate d by a repulsive potential correlated with Kr 5p[3/2]1 + Kr(1S0). The lowest ionization limit of Kr2 (relative to a 3SIGMA(u)+, v = 0) was d etermined to be 28 484 +/- 5 cm-1.