Abstract: A method and apparatus, for supplying high-pressure mixed gas of a low-vapor-pressure first gas as an active gas and a high-vapor-pressure second gas, are arranged to reduce an amount of the first gas discarded. The mixed gas in a high-pressure state is supplied from a mixing container to a use point. Upon reduction of pressure in the mixing container to a setpoint as a result of supply to the use point, a predetermined amount of the first gas is charged into a replenishment container connected to the mixing container by a replenishment line having a replenishment valve, and which is evacuated. As the second gas is charged into the replenishment container charged with the first gas, the replenishment valve is opened such that the first gas in the replenishment container is forced out by the second gas, thereby charging the mixing container with the mixed gas in the high-pressure condition.

Abstract: A method and apparatus, for supplying high-pressure mixed gas of a low-vapor-pressure first gas as an active gas and a high-vapor-pressure second gas, are arranged to reduce an amount of the first gas discarded. The mixed gas in a high-pressure state is supplied from a mixing container to a use point. Upon reduction of pressure in the mixing container to a setpoint as a result of supply to the use point, a predetermined amount of the first gas is charged into a replenishment container connected to the mixing container by a replenishment line having a replenishment valve, and which is evacuated. As the second gas is charged into the replenishment container charged with the first gas, the replenishment valve is opened such that the first gas in the replenishment container is forced out by the second gas, thereby charging the mixing container with the mixed gas in the high-pressure condition.

Abstract: The present invention relates to a method for producing a fluoroalkylsulfonic acid anhydride represented by a general formula of (C.sub.n F.sub.2n+1 SO.sub.2).sub.2 O where n is an integer ranging from 1 to 8. This method includes a step of (a) reacting diphosphorus pentoxide with a fluoroalkylsulfonic acid represented by a general formula of C.sub.n F.sub.2n+1 SO.sub.3 H where n is an integer ranging from 1 to 8, in a fluorine-containing solvent, thereby to form the fluoroalkylsulfonic acid anhydride in the fluorine-containing solvent. A fluoroalkylsulfonic acid anhydride produced by this method is high in purity and yield.

Abstract: A laser gas used in a rare gas fluoride excimer laser is efficiently refined with little loss of the principal rare gas such as Ar, Kr or Xe by sequential contact of the laser gas first with a reactive metal, e.g. Si or Fe, for conversion of the fluorine source gas such as F.sub.2 or NF.sub.3 to a metal fluoride, then with a solid alkaline compound, e.g. Ca(OH).sub.2, for conversion of gaseous fluorides to solid metal fluorides, next with zeolite which is adsorbent of most of the remaining impurities and finally with an alkaline metal, e.g. Ca or Na, for decomposition of CF.sub.4 to form a solid metal fluoride and carbon. CF.sub.4 is formed during operation of the excimer laser by reaction of fluorine with a fluororesin used as electrical insulator in the laser apparatus, and accumulation of CF.sub.4 in the laser gas caused significal lowering of the laser output power.