Empty levels probed by XAS and ETS in cyclic polymethylene sulfides (CH2)(n)S, n=2, 3, 4, 5

The sulfur K-shell photoabsorption spectra (XAS) and the electron transmiss ion spectra (ETS) have been obtained for a series of cyclic polymethylene s ulfides (CH2)(n)S with n = 2, 3, 4, 5. These spectra are dominated by simil ar broad resonances with trapping of the impinging (ETS) or K-shell excited (XAS) electron in sigma*(S-C) and pi*(CH2) orbitals. Calculation of the el ectron affinity is performed with the DFT/B3LYP technique and its evolution through this cyclic series and the corresponding open chain series of mole cules shows good agreement with experimental results, enlightening the role of molecular strain in lowering the sigma*(S-C) level in the three- and fo ur-membered ring thio compounds. (C) 2001 Published by Elsevier Science B.V .