THE ELECTRONIC-STRUCTURE OF POLY(PYRIDINE-2,5-DIYL) INVESTIGATED BY SOFT-X-RAY ABSORPTION AND EMISSION SPECTROSCOPIES

The electronic structure of the poly-pyridine conjugated polymer has b een investigated by resonant and non-resonant inelastic X-ray scatteri ng and X-ray absorption spectroscopies using synchrotron radiation. Th e measurements were made for both the carbon and nitrogen contents of the polymer. The analysis of the spectra has been carried out in compa rison with molecular orbital calculations taking the repeat-unit cell as a model molecule of the polymer chain. The simulations indicate no significant differences in the absorption and in the non-resonant X-ra y scattering spectra for the different isomeric geometries, while some isomeric dependence of the resonant spectra is predicted. The resonan t emission spectra show depletion of the pi electron bands in line wit h symmetry selection and momentum conservation rules. The effect is mo st visual for the carbon spectra; the nitrogen spectra are dominated b y lone pair n orbital emission of sigma symmetry and are less frequenc y dependent. (C) 1998 Elsevier Science B.V. All rights reserved.