A non-selective light-induced reaction was observed in the spectral range from 135 to 120 nm due to electronic excitation of Cl-2 in the gas phase to the (1)Sigma(u)(+) and 2(1)Sigma(u)(+) states. It reaches a quantum efficiency of reacted Cu per impinging photon of 174 and the underlying amplification process has an efficiency of 4 x 10(6). A selective reaction dominates between 135 and 200 nm with two prominent bands at 170 and 144 nm. It originates from a bulk-excitation with a quantum efficiency of two reacted atoms per photon.