An intense beam of the dimer anion of CS2 was prepared by a pulsed-discharge nozzle, which enabled the measurement of the previously-reported 2.7-eV photoelectron band of C2S4- with higher spectral resolution at 355 nm. This measurement has revealed that the band consists of a vibrational progression with an average spacing of 0.13 +/- 0.01 eV, indicating a bound electronic property of the residual C2S4 neutral. With the aid of molecular orbital calculations, the observed progression has been assigned to the transition from C2S4-(B-2(1)) to the vibrationally-excited states of C2S4 ((1)A(1)), both possessing cyclic C-2v structures. (C) 2008 Elsevier B.V. All rights reserved.