Light induced suppression of sulfur in a cesium sputter ion source

► The effect of cw laser light on the production of S− and Cl− was studied. ► The S− current was reduced by one order of magnitude with 100 mW of laser power. ► The Cl− current became enhanced. ► Time structure and power dependence of the effect were investigated. ► The effect was successfully applied in a regular AMS 36Cl measurement.