Effect of electron scavengers on the gamma radiolysis of H²S-Ch³Br systems

Abstract

Recent publications (1 4) have dealt with the effect of electron scavengers on the radiolysis of simple inorganic gaseous hydrides. We would like to present some results of a preliminary study on the radiolysis of gaseous H2S that are, in general, quite different from those above (14). Matheson C.P. grade H,S (99.7 %) was found to contain CO, (-0.2 %) and CS, (< 0.001 %) as impurities when checked by gas chromatography. A 3 m Poropaq Q column maintained at 65 "C, helium carrier gas, and thermal conductivity detection were used (5). After several freeze-pump-thaw cycles at-130 "C, the concentration of CO, was reduced to-0.005 %. Some of this H,S was irradiated to a dose of about 4 x lo2, eV g-l. After degassing at-196 "C, this H,S was found to contain-0.005 % CO, and no detectable amount of CS,. Radiolysis experiments with the pre-irradiated H,S gave identical results to the untreated H,S, and so the latter was used for the bulk of the work presented here. SF, and N,O (Matheson) were degassed several times by freeze-pump-thaw cycles at liquid nitrogen temperature and were used without further purification. Dosimetry was effected by ion current measurements in vessels similar to those described by Back et al. (6), the extrapolation method of Scott and Greening (7) being used to obtain saturation ion currents. The same vessels were also used as irradiation vessels, as were ordinary Pyrex vessels of similar geometry. All vessels were baked out at 400 "C, to a pressure of less than lo-' Torr prior to filling and irradiating.