Central Glass Company, Limited

Hiroshi Ichimura

Minoru Aramaki

Shinsuke Nakagawa

Hisaji Nakano

Masahiro Tainaka

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.

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Ube, Japan

Hiroshi Ichimura