Dosed on oxidized Si(100) at 100K, carbon tetrachloride adsorbs and desorbs without dissociation. The monolayer desorbs at 135 K, 10 K lower than the multilayer. This unusual behavior is attributed to stronger interactions between condensed CCl4 molecules than between CCl4 and SiO2. Irradiation with either low-energy (less than or equal to 50 eV) electrons or Mg K alpha x rays causes C-Cl cleavage. For 50 eV incident electrons, the decay of the CCl4 temperature programmed desorption peak area occurs with an effective cross section of (2.0+/-0.1)x10(-16) cm(2). The same cross section characterizes the ejection of CCl (CCl+) during electron irradiation. After low electron fluences, C-2 and C-3 molecules desorb reflecting both electron-induced C-Cl bond dissociation and C-C bond formation. At 2.5 eV incident electron energy, the cross section is still high-10(-17) cm(2). Electron activation is attributed to a combination of impact ionization and electron attachment mechanisms.