The Na-2 4(3s + Sd) (3) Delta(g), 7(3s + 6d) (3) Delta(g), and 10(3s + 7d) (3) Delta(g) states have been observed and studied by pulsed perturbation facilitated optical-optical double resonance (PFOODR) spectroscopy for the first time. Spectroscopic constants of the 4(3) Delta(g) and 7(3) Delta(g) states and the corresponding RKR potential curves have been obtained. The major molecular constants obtained are: [GRAPHICS] A quantum defect analysis of the 3s + nd (n = 3-7) (3) Delta(g) series gives a quantum defect, mu, of -0.0946(2). (C) 1996 Academic Press, Inc.