Electron Paramagnetic Resonance of Sulfur Monoxide

Abstract

Four electron paramagnetic resonance transitions of the SO free radical generated in a gas‐phase discharge of SO₂ have been observed and assigned. The lines result from electric‐dipole transitions between the Zeeman levels of the K = 1, J = 1 → K = 2, J = 1 states of the ³Σ⁻ electronic ground state of ³²S¹⁶O and ³⁴S¹⁶O. The rotational constant B₀ and the splitting constants λ and μ have been obtained from the microwave investigation of Powell and Lide. The g values of the electron spin, the orbital, and the rotational magnetic moments of ³²S¹⁶O as determined from least‐squares fitting of the EPR data are g_s = 2.00197, g_l = 0.00371, and g_r = 0.00019. The frequencies of the corresponding transitions for the less abundant species, ³⁴S¹⁶O, have been calculated from the isotope corrected ³²S¹⁶O parameters. The relative intensities and linewidths of the SO spectrum are discussed. The linewidth is attributed to the collision broadening of SO by SO₂.