Optical-optical double resonance spectroscopy of I-2 through the parity mixed valence states

We used the perturbation-facilitated optical-optical double resonance techn ique to access the ungerade ion-pair states of I-2 using the (1 + 1) photo- excitation sequence through the B(3)Pi (0(u)(+))-c1(g) parity mixing states . By analyzing the second step of the double resonance to the F0(u)(+) ((3) p(0)), gamma1(u)((3)p(2)), and H1(u)(P-3(1)) states, the g-u coupling schem es were elucidated in the intermediate B(3)Pi (0(u)(+))-c1(g) state. We wer e also able to populate the delta2(u)(P-3(2)) state through the g-u mixing state, and to improve its molecular constants. The interference effect betw een the parallel gamma1(u)(P-3(2))-c1(g) and perpendicular delta2(u)((3)p(2 ))-c1(g) transitions was used to derive the ratio of their electronic trans ition moments, (mu (e)(parallel to)/mu (e)(perpendicular to)) similar to 5. 5.