Size dependency of soft X-ray emission spectra. Calculations on finite polyenes and polyacetylene

We explore the size dependency of soft X-ray emission spectra by means of Hartree-Fock calculations of polyenes up to C28H30 and by band structure calculations of the X-ray emission spectrum of polyacetylene. It appears that oligomers with a chain length of around ten unit cells display quite complex spectral features and show intensity in regions where neither the monomer nor the polymer have appreciable intensity. For the longer oligomers the spectra are simplified, and converge to a polymer spectrum with some remarkable molecular-like features.