Appeal No. 95-2231 Application No. 08/114,285 Claims 31 and 32 are illustrative of the subject matter on appeal and read as follows: 31. A method of extending the continuous operating life of an excimer laser containing a lasing gas or gas mixture selected from the group consisting of XeF, KrF and ArF, by removing an amount of CF impurity therefrom during operation 4 of said excimer laser, which is sufficient to minimize loss of laser power output and to extend the continuous operating life of said excimer laser, which comprises: a) introducing oxygen into said lasing gas or gas mixture, and reacting said oxygen with said CF impurity which 4 accumulates in said lasing gas or gas mixture, said oxygen being introduced in an amount effective to produce one or more compounds which are condensable with refrigeration means; and b) condensing said one or more or more compounds produced in step a) in cryogenic trap, with refrigeration means and at a temperature sufficient to condense said one or more compounds substantially without condensing said lasing gas or gas mixture therewith, thereby removing said CF4 impurity from said lasing gas or gas mixture, thereby extending the operating life of the excimer laser. 32. A method of extending the continuous operating life of an excimer laser containing a lasing gas or gas mixture selected from the group consisting of XeF, KrF and ArF, by removing an amount of oxygen impurity therefrom during operation of said excimer laser, which is sufficient to minimize loss of laser power output and to extend the continuous operating life of said excimer laser, which comprises: 2Page: Previous 1 2 3 4 5 6 7 8 NextLast modified: November 3, 2007