The (5)<sup>1</sup>Σ?????? state has been studied by two-step excitation spectroscopy. 270 levels in the state were measured with high resolution. A set of Dunham coefficients was deduced to fit all levels with v < 19. The spectroscopic data were used to construct a Rydberg—Klein—Rees potential for the state. The potential shows that the state is perturbed by other Rydberg states and ionic states and seems likely to have a second well that is due to avoided crossings with these states.
© 1988 Optical Society of America
G.-Y. Yan, B. W. Sterling, and A. L. Schawlow, "Potential of the (5)1Σ+g state of Na2 by two-step excitation spectroscopy," J. Opt. Soc. Am. B 5, 2305-2310 (1988)