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Unoccupied electronic states near the Fermi level of poly(dimethylsilane) were probed using Si 1sX-ray absorption spectroscopy (XAS) and SiKL2,3L2,3resonant Auger spectroscopy (RAS). The measured resonance peaks of XAS spectra near SiK-edge have been assigned in comparison with the discrete variational (DV)-Xα molecular orbital calculations. The rapid delocalization of Si 1score-excited electron through the empty conduction band was observed along the polymer chain with the energy-dependent RAS measurement, and the electron delocalization time was estimated based on the core-hole clock method. [ABSTRACT FROM AUTHOR]

The electronic properties of polycrystalline 6,13-Bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) was probed by inner-shell spectroscopies such as near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and electron emission spectroscopy at the SiK-edge. Although the lowest unoccupied molecular orbital (LUMO) near the Fermi level is mainly on the acene unit, a small LUMO peak was observed in Si 1s NEXAFS spectra. Angle-dependent NEXAFS spectra indicate that a well-ordered structure is produced in the polycrystalline TIPS-pentacene. It was demonstrated that randomly oriented small single-crystal grains can be aligned by rubbing the powder sample. [ABSTRACT FROM AUTHOR]