PERTURBATION FACILITATED OPTICAL-OPTICAL DOUBLE-RESONANCE SPECTROSCOPY OF THE 2(3)SIGMA(+)(G),3(3)SIGMA(+)(G), AND 4(3)SIGMA(+)(G) RYDBERG STATES OF LI-7(2)

This paper reports the experimental observation of the 2 3Σg+, 3 3Σ g+, and 4 3Σg+ states of 7Li2 by cw perturbation facilitated optical-optical double resonance spectroscopy. Molecular constants and RKR potential curves have been obtained. Our experimental Te and R e for the 2 3Σg+ state are 27 297.45(16) cm-1 and 3.0797(18) Å, respectively, and for the 3 3Σg+ state are 31 043.93(53) cm -1 and 3.0378(19) Å, respectively. The above values are in very good agreement with theoretical calculations. Hyperfine splitting for both states has been resolved. Both states follow Hund's case (bβS) hyperfine coupling scheme. The experimental Fermi contact parameter, b F, is approximately 96±2 MHz for the 2 3Σ g+ state and 95.6±3 MHz for the 3 3Σg+ state. These values are in good agreement with the previously obtained value 98.6±4 MHz [Li et al., J. Chem. Phys. 96, 3342 (1992)]. One level of the 4 3Σ g+ state has been observed and its hyperfine structure has been resolved and characterized with Hund's coupling case (b βS). © 1995 American Institute of Physics.