QUANTUM-STATE-RESOLVED 2-LEVEL FEMTOSECOND ROTATIONAL COHERENCE SPECTROSCOPY - DETERMINATION OF ROTATIONAL-CONSTANTS AT MEDIUM AND HIGH J IN LI-2, A SIMPLE DIATOMIC SYSTEM

A series of rotational wave packet recurrences originating from single 2-level coherent rotational superpositions are observed in the E((1) Sigma(g)(+)) state of Li-2. The rotational wave packet is created by u ltrafast laser excitation from a specific re-vibrational level in the A((1) Sigma(u)(+)) state selected by cw laser excitation. Using this t echnique the rotational constant and the centrifugal distortion consta nt are determined for high J levels of the upsilon=9 vibrational level in the E((1) Sigma(g)(+)) state. This technique is discussed vis-a-vi s traditional forms of ultrafast rotational coherence spectroscopy whe re information primarily at low J is obtained.