Temporary anion states of sulphur derivatives of γ-pyrone

The electron transmission spectra of 4H-thiopyran-4-one. 4H-pyran-4-thione and 4H-thiopyran-4-thione have been recorded in the 0–6 eV energy range and the observed resonances assigned to the corresponding anion states. Unlike γ-pyrone, its sulphur derivatives possess low-energy Σ anion states.