Observation of the [7.sup.1][II.sub.g] state of [Na.sub.2] by optical-optical double resonance spectroscopy

The high-resolution cw optical-optical double resonance spectroscopic study observation for the [7.sup.1][II.sub.g] Rydberg state of [Na.sub.2] correlating with the separated atom limit Na(3s) + Na(5p) is presented. The observation of the [7.sup.1][II.sub.g] state in the [Na.sub.2] system could be applied to study the higher Rydberg states of [Na.sub.2] and other alkali dimers and gain insight into interactions in diatomic molecules.