Energy Partition in the y-Radiolysis of Gaseous H2S+N2, H2S+Ar and H2S+Xe Mixtures

Abstract

Ionization measurements in H24-N2, H2S4-Ar, and H2S4-Xc mixtures arc used to determine apparent stopping power ratios for the mixtures, or “ energy partition parameters ”. The values found for H2S4- N2, H2S4-Ar, and H2S4-Xc are 0.20, 0.95, and 3.60 respectively, as compared to the calculated values of 0.82, 0.95, and 2.46. In H2S4-Ar mixtures a “Jesse effect ” is observed that increases the ion yield by 2 units, this effect being quenched out between stopping power fractions Z = 0.2-0.4. Measurement of sulphur yields in H2S4-N2 mixtures enables an energy partition parameter of 0.5 to be evaluated. The difference from the value obtained by ionization measurements being explained by a small “Jesse effect" In H2S4-Ar mixtures the sulphur yield G(S) was always >G(S) = 7.0 found in pure H2S and approached values as high as 24. The sulphur yield also increased between Z = 0.2 and 0.4 by twice the decrease in the ion yield. G(S) in H2S4-Xe mixtures never rises above 7.0, and the values can be justified by energy transfer from Xe* (G ~ 5.0) to H2S to give H2 4- S*, where S* is not a ground state S(3P) atom. No such simple mechanism will explain the results in H2S4-Ar mixtures. Butadiene was used as an SH and S(3P) scavenger, and the ratio of scavengeablc to non-scavengcablc sulphur in H2 4-Ar mixtures is similar to that in H2S i.e. ^43. In H2S4-Xc mixtures this ratio is ~3-4, and is explained by production of excited S atoms (S*), which react with H2S to give H2 and S2.