Gerade Rydberg states of Xe-2 lying 12500-14800 cm(-1) above the a(3)Sigma(+)(u) (1(u), O-u(-)) metastable levels of the dimer have been observed by laser spectroscopy in the afterglow of a Xe microplasma with a volume of similar to 160 nL. Photoexcitation of Omega(g) <- a(3) Sigma(+)(u)(1(u), O-u(-)) (Rydberg Rydberg) state transitions at small internuclear separations (R similar or equal to R-e(Xe-2(+))) while monitoring the suppression of 2 Xe-2(O-u(+) -> O-g(+)) spontaneous emission in the ultraviolet confirms the presence of an extensive series of red-degraded vibrational bands 9 in the 675-800 nm region that are tentatively identified with an Omega = 1 upper state with a molecular ion core having predominantly B-2 Pi(3/2g) character. Spectral simulations yield the following constants for the 1(g) state: R-c' = 3.49 +/- 0. 1 angstrom, T-e = 12 980 +/- 70 cm(-1), omega(e)' = 122 +/- 3 cm(-1), omega'(e)x(e)' =0.9 +/- 0.2cm, and D-e' =2250 +/-70cm. (c) 2006 Elsevier B.V. All rights reserved.