Synthesis of krypton and lower xenon fluorides in a glow discharge

Abstract

The synthesis was carried out by electric discharge in a reactor cooled by liquid nitrogen. The conditions of the experiment were the following: voltage 10–15 kV, discharge current 20–50 mA, distance between electrodes 100– 450 mm, fluorine pressure 4–30 torr. The dependencies of the output of KrF 2 on the electric discharge capacity, fluorine pressure, diameter of the discharge tube and the temperature will be presented. At 77 K the output of KrF 2 is 5–8 g/(kW h), and at 67 K it is 25–30 g/(kW h). In a first approximation the reaction rate is described by a kinetic equation of first order in fluorine: d[KrF 2]/ dτkS Kr[F 2]W Only pure xenon difluoride is formed in the solid xenon matrix, if the degree of xenon conversion doesn't exceed 50%. Under higher degrees of conversion XeF 4 and XeF 6 are formed. Conditions under which the mentioned compounds could be obtained in pure form were determined. The output of XeF 2 exceeds 600 g/(kW h). The results obtained are explained by assuming the formation of intermediate KrF and XeF radicals (NgF). In this case the output of the lower xenon fluorides is determined by the conditions of radical formation and further reaction: NgF (s)+F→NgF 2(s) NgF (s)+NgF (s)→NgF 2(s) + Ng (s) + Q 1→2Ng (s)+F 2+Q 2 NgF (s)+F→NgF 2(s)+Q 3→Ng (s)+F 2(g)+Q 4 In general the output of NgF 2 is determined by the effectiveness of atomic fluorine generation and intermediate radical activity.