Knowledge Bank

Optical-Optical Double Resonance (OODR) was employed to excite rovibrational levels in the unknown upper portions of the G(1)$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Pi g$ and F(4)$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+$ states. Although both are singlet states and dissociate to the same atomic limit (2p+2p) they behave in significantly different ways. Vibrational levels as high as v = 48, which has rotationless energy within 1% from the dissociation energy, were observed in the $G1\Pi g$ state by detecting molecular fluorescence. In the $F1\Sigma g+$ state all levels in the energy region above 2s+3s atomic limit were found to the strongly predissociated. This is due to interactions with the continuum of the $E1\Sigma g+$ state which at long internuclear distance dissociates to the 2s + 3s atomic limit. Because of the very short lifetimes these levels were detected using atomic side fluorescence. A $C5$ coefficient was determined from the last few outer turning points of the experimental RKR potential curve of the $G1\Pi g$ state. Rotational and vibrational dependence of the line width for the predissociated $F1\Sigma g+$ state levels was investigated and a preliminary RKR curve which covers 99.6% of the potential well has been derived from experimental data.