Abstract: A closed-cycle gas scrubbing or purification system is described for noble gas and fluorine mixtures, such as are typically used in rare-gas fluoride (excimer) lasers. In a first reaction zone, the fluorine in the gas mixture is converted to titanium tetrafluoride vapor by reaction with titanium at a temperature above 150 degrees C., preferably at about 300 degrees C. The TiF.sub.4 vapor is then removed without passivating the titanium by condensing the TiF.sub.4 vapor in a separate condensation zone held at a temperature below the temperature of the first reaction zone, preferably at about room temperature. After condensing the TiF.sub.4 from the gas mixture, any silicon tetrafluoride in the mixture is chemically removed by contacting the gas mixture with an alkaline earth oxide (preferably either CaO or MgO) in a second reaction zone. Residual contaminants (i.e., contaminants other than SiF.sub.