Inner shell excitation of SO2 by high-energy electron impact: a comparison with multichannel quantum defect theory

High-resolution electron energy loss spectra of the sulfur 2p, 2s and oxygen 1s inner shells of SO₂ have been obtained under conditions of high impact energy (1–3 keV) and zero-degree scattering angle. The results are also compared with photoabsorption spectra in the sulfur 1s and 2p regions. Multichannel quantum defect theory calculations of energies and oscillator strengths for S 2p, 2s, O 1s and S 1s are in excellent quantitative agreement with the measurements and are used to assign the spectra.