The optical and electron resonance spectra of SO3-

Abstract

The ionic radical SO₃ ^- has been identified in γ-irradiated single crystals of sodium dithionate, sulphamic acid, potassium sulphamate, potassium amine disulphonate and potassium methane disulphonate. The electron resonance spectrum is a single line with an isotropic g factor of 2·004. The principal values of the ³³S hyperfine coupling tensor are 428, 314 and 316 Mc/s, from which the percentages of 3s and 3p character of the unpaired electron orbital are obtained, enabling a value of 111° for the O-S-O angle to be deduced. Ultra-violet transitions at 2700 å and 2400 å were found for SO₃ ^-. A value of 10⁴ for the extinction coefficient of the 2400 å band was measured. A comparison of spin populations between the isoelectronic species PO₃ ⁼, SO₃ ^- and ClO₃ is included.