?-Radiolysis of gaseous H2S + SF6 mixtures

Abstract

Measurement of G(ion) (= 1 0 0 / W ~) and G(H& in H2S+SF6 mixtures, where WM is the average energy required to produce an ion pair in the mixture, and G(ion) and G(H~)M are the total ion yield and hydrogen yield respectively, enables energy partition parameters a to be calculated. These were found to be a = 1.44 for mixtures of stopping power fraction 2 = P1/(Pl+S2P2/Sl), (where P and S refer to pressure and stopping power of gases 1 and 2) between -h 0.2 and 1 .O. Below 2 -I I . 0.2 each mixture has its own particular a value and these values, in the main, decrease smoothly with decreasing 2 to a e 0.70 at 2 = 0.02. The hydrogen produced in the mixtures from energy deposited in H2S alone, G(H~)H~s, is independent of SF6 concentration when energy partition is calculated using these a parameters.Sulphur yields in the mixture G(S)M are much greater than G(H& ; the imbalance is accountable by HF production. At low SF6 concentration (high Z), G(S)M inneases rapidly with SF6 concentration fram 7.0 in pure H2S to 11.0 at 2 = 0.98 (3; mol % SF6).Recent work on the a-particle and y-ray irradiation of gaseous H2S has demonstrated that electron scavengers such as 02, N20, SF6, do not lower the radiation yield of hydrogen, G(H,). In fact, as the SF6 concentration is increased to 7 mol %, G(H,) increased from 7.0 to 8.0.2 In experiments using very high dose rates from a 600 kV electron pulse, Perner and Franken observe the lowering of G(H2) by the addition of SF6.The effect of SF6 on G(H,) observed by us may be due to energy transfer from SF6 to H2S. To test this possibility and perhaps gain information on the radiolysis mechanism, we decided to measure the W values and product yields, G(H2) and G(S), of binary mixtures of H2S and SF6 over the whole concentration range. EXPERIMENTALThe treatment of H2S, SF6 and all other materials used, irradiation equipment and procedure, ion current measurements, and hydrogen and sulphur analyses, have all been described previously. 3 SiF, was detected by I.R. and mass spectroscopy. Infra-red measurements were carried out on a Unicam SP200 spectrophotometer, using a 0.1 m gas cell having sodium chloride windows.Mass spectra were obtained on an A.E.I. MS12 instrument.

The High Dose Rate Radiolysis of H2S: Sulfur as an Electron Scavenger

“…Rcently several studies of the radiolysis of hydrogen sulfide have been reported (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) and we have proposed a mechanism based on our measurements at high dose rates (13). While this mechanism is in general agreement with the observed yields there are problems which need further investigation.…”

“…At high dose rates for single pulse irradiations in pure H,S, charge neutralization involves the free electron, reaction 1 . 3 On the addition of SF,, SF6-is involved in the neutralization step and the formation of hydrogen atoms, [I], is suppressed.…”