Radiation chemistry of liquid hydrogen sulphide

Abstract

G(H₂) for cobalt-60 γ-irradiated liquid hydrogen sulphide at –78°C is 8.1±0.3 and is unaffected by the addition of I₂ or DPPH. G(S) is 6.6±0.7 for the pure liquid, and when DPPH is present increases through a flat maximum about 8 at DPPH concentrations of 10^–4 to 10^–3 M, thereafter decreasing to 3 in 10^–2 M DPPH. The yields suggest that H atoms abstract hydrogen atoms from the solvent, and SH radicals combine to form H₂S and S atoms which later polymerize. Although H₂S₂ was not detected, the lack of stoichiometry suggests it is formed in the pure liquid and the following yields were calculated assuming G_H2 is zero. G_H=G_–H2S= 8.1±0.3; G_SH= 5.1±1.7; G(H₂S₂)= 1.5±1.0. The value for G_–H2S is greater than the maximum value calculated from mass spectrometric and ionization efficiency data for the reactions of the primary ions alone and suggests that some decomposition may result from excitation also. The ineffectiveness of I₂ and DPPH in changing G(H₂) is probably due to an inability to add sufficient of these solutes to compete with solvent for H atoms. In iodine solutions, sulphur is formed in a chain reaction.