STUDY OF RB2 LONG-RANGE STATES BY HIGH-RESOLUTION PHOTOASSOCIATION SPECTROSCOPY

We study the states of Rb2 that lie within 35 cm-1 of the 5(2)S1/2 + 5(2)P3/2 dissociation limit with photoassociation spectroscopy of laser-cooled Rb atoms. We observe the rotationally resolved bound levels of the novel 0g- ''pure long-range'' state, which has an inner turning point beyond 25 bohrs. We also identify levels belonging to 1g and 0u+ states and find that the 0u+ levels are broadened by predissociation. With our new method, excited molecular states with a binding energy from less than 0.3 to more than 1000 cm-1 can be studied with a resolution better than 0.002 cm-1.