High resolution spectra of the (2)(IIu)-I-3[Omega=0(+) and 1](upsilon,J)<--X (1)Sigma(g)(+)(upsilon ",J ") transitions of the Cs-2 molecule in the 15 400- 16 000 cm(-1) region are measured by the technique of Doppler-free optical-optical double resonance polarization spectroscopy (OODRPS). Molecular constants of the (2)(II0+u)-I-3(upsilon=0-18) and (2)(II1u)-I-3(upsilon=0-13) levels are determined, and potential energy curves are constructed by the RKR method. The RKR potentials are found to be in very good agreement with the ab initio potentials computed by Spies. OODRPS spectra of the (CIIu)-I- 1(upsilon＇= 19- 21,J＇) <--X (1)Sigma(g)(+) transitions are measured in order to expand the data on the C (IIu)-I-1 state. We reconsider the perturbation of the C (IIu)-I-1(upsilon＇greater than or equal to 13,J＇) levels, and the perturbing state is identified as the 1(u)[(2)(3)Sigma(u)(+)+(2)(IIu)-I-3] state. The molecular constants of the perturbing state are determined to be T-e = 16 332.3 cm(-1), omega(e) = 21.9 cm(-1), and B-e= 0.007 94 cm(-1),.and the potential is constructed by the RKR method. Energy shifts of both e and f levels of the C (IIu)-I-1 state centered at the same J and the hyperfine splittings are identified as the results of spin-orbit coupling between the C (IIu)-I-1 and 1(u)[(2)(3)Sigma(u)(+) +(2)(IIu)-I-3] states. Another type of energy shifts observed in only f level of the C (IIu)-I-1 state is identified as the results of the L-uncoupling interaction between the (2)(3)Sigma(u)(+)[0(u)(-)(c)] state and the C H-1(u) state which is mixed with the (2)(IIu)-I-3[1(u)(a)] state by spin-orbit coupling. Line broadenings observed in the C (IIu)-I-1(upsilon＇greater than or equal to 16) levels are identified as originating from the predissociation, which arises from interactions with the repulsive part of the 1(u)(a) state which has the potential hill with;a peak of 16 420 cm(-1) at about 6.6 Angstrom.