The hyperfine structure of the 1 (3)Delta(g) state of Na-2

The hyperfine spectra of the Na-2 1 (3)Delta (g) state have been recorded w ith sub-Doppler continuous wave (CW) perturbation facilitated optical-optic al double resonance (PFOODR) spectroscopy via A (1)Sigma (+)(u)similar tob (3)Pi (u) mixed intermediate levels. The rotational lines into the N=14-51 levels of the 1 (3)Delta (g) state observed previously [J. Mol. Spectrosc. 134, 50 (1989)] have four components for transitions between symmetric rota tional levels or five components for transitions between antisymmetric rota tional levels and the hyperfine coupling belongs to Hund's case b(betaS). F or the low-N levels observed later, however, the hyperfine spectra are much more complicated. We have worked out the matrix elements of the molecular Hamiltonian in the case b(betaS) basis. After taking into consideration spi n-orbit, spin-spin, and spin-rotation interactions, we obtained a set of mo lecular constants for the Na-2 1 (3)Delta (g) state, with which we can repr oduce the hyperfine spectra of both high- and low-N rotational levels. (C) 2001 American Institute of Physics.