High resolution absorption spectra of the C (1)Pi(u)<--X (1)Sigma(g)(+) transition of the Na-23(2) molecule have been measured in the range 29 680-30 950 cm(-1) by exploiting the technique of Doppler-free UV-visible optical-optical double resonance polarization spectroscopy. The molecular constants of the C (1)Pi(u)(v=0-10) levels are determined, and the Rydberg-Klein-Rees potential energy curve is calculated. A number of C (1)Pi(u)(v=0-9,Je and f ) levels were found to be perturbed. The energy shifts of e and f parity levels of the C (1)Pi(u) state were studied and identified as originating from perturbations between the C (1)Pi(u) and 3 (3)Sigma(u)(+) states. Remarkable line broadenings were observed only in the perturbed region and identified as the lifetime broadening effect originating from indirect (accidental) predissociation through the two diabatic (3)Sigma(u)(+) states. (C) 2003 American Institute of Physics.