Analysis of the composition and utilization of fluorine-containing gas mixtures for excimer lasers

A technique for analysis of fluorine-containing gas mixtures for excimer lasers, which provides fluorine determination in the range of 0.1 – 5 % mol. with a relative error of less than 6 % is presented along with an installation intended for the composition control of the aforementioned mixtures. Known industrial processes of removing fluorine from gaseous wastes suggest using of active alumina. We measured the adsorption capacity of alumina with respect to elemental fluorine, however, the measured value turned out to be two orders of magnitude less than the theoretical value calculated under the assumption of monomolecular adsorption (0.255 g F/1 g of adsorbent) which can be attributed to a low adsorption activity of the alumina surface. To activate the adsorbent surface, halogen-containing activators — potassium bromide and potassium iodide — were tested, which interact with fluorine, turning it into non-volatile potassium fluoride and free bromine or iodine. These components are well adsorbed on alumina, giving it a yellow or brown color. Activation of the adsorbent surface is proved experimentally, since the capacity of the activated sorbent is fifteen times as much the amount of fluorine bound by a chemical reaction, and the total adsorption capacity of aluminum oxide increases by a factor of 80 compared with an inactive adsorbent.

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