Radiolysis of Hydrogen Sulfide at Very High Dose Rates. The Effect of SF₆¹

Abstract

Gaseous H2S has been irradiated with electron pulses from a Febetron 705 at a dose rate of ~2 × 1027 eV g−1 s−1. For single pulse experiments, the yield of hydrogen is G(H2) = 12.0 ± 0.5, independent of pressure from at least 350 to 1600 Torr. Addition of SF6 reduces the yield to G(H2) = 7.9 ± 0.3 which is fairly close to that observed for pure H2S at low dose rates. The reduction, ΔG(H2) = 4.1 ± 0.3, agrees very well with the ion pair yield based on a W value of 25.3 eV.In multi-pulse irradiations, for pure H2S, the yield falls off with dose giving a limiting yield close to G(H2) = 8.0. No similar fall-off is observed for H2S–SF6 mixtures. It is proposed that at high absorbed doses and at low dose rates, there is no contribution to the hydrogen yield from neutralization processes; and that this is due to neutralization of H3S+ by an ion of the type Sn− rather than a free electron.

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.…”

“…The proposed mechanism does not predict any dose rate effect in the range 10' ' -10'' eV g-' s-', yet we observed an increase from G(H2) = 12.0 f 0.5 to G(H2) = 13.1 f 0.4 over this range (13,14). To study this further we have measured HZ yields in both pure H2S and H2S-SF, mixtures from 1 x loz6 eV g-' s-I to 2 x 10' ' eV g-' s-I at room temperature.…”

“…For H2S-SF, mixtures no similar reduction with dose is observed (13), the hydrogen yield remaining constant at G(H2) = 7.9.…”

“…Addition of compounds capable of electron attachment, N,O or SF,, does not reduce this hydrogen yield. At high dose rates (lo2, -loz8 eV g-' S-I) the yield is much higher G(H2) = 11.5-13.0 (12)(13)(14) and appears to increase with dose rate over this range. At 2 x loz7 eV g-' s-I the hydrogen yield G(H2) = 12.0 0.3 is reduced to G(H2) = 7.9 + 0.3 by the addition of SF6 (13).…”

Radiolysis of methane. Formation of acetylene

“…Field emission sources delivering -60 and -3 ns pulses (Febetron 705 and 706) were used in the pulse radiolysis experiments. The dose per pulse was determined using N 20 as a dosimeter [12], taking G(N z ) = 12.4. The reaction vessels used in the pulse radiolysis experiments were cylindrical vessels (5 em long and 3.7 em internal diameter).…”