We report electron-energy-loss spectra of solid films of CO2 for electronic transitions induced by 15, 19.4, and 25 eV incident electrons. All spectra were obtained under sufficiently small electron exposures so as to avoid sample damages. The use of a low-energy electron along with the backscattering geometry give access to spin- and symmetry-forbidden transitions while the effect of the condensed phase makes it possible to modify the energy, ordering, and magnitude of most gas-phase transitions. The most noticeable observation is the disappearance of all sharp energy-loss peaks attributed to a Rydberg series of CO2 in the gas phase. In contrast, transitions to the molecular valence (3,1)Delta(u) and (3,1)Sigma(u)(-) states are located virtually at the same energy as in the gas phase. The strong dipole-allowed valence (1)Sigma(u)(+) transition is found shifted to lower energy by about 0.3 eV while transitions to mixed Rydberg-valence (3,1)Pi(g) and (1)Pi(u) states are both shifted to higher energy by about 0.4-0.5 eV. The lowest valence (3)Sigma(u)(+) transition is ascribed to the lowest energy-loss feature in the solid at 7.9 eV. (C) 2003 American Institute of Physics.