High-resolution inner-shell excitation spectroscopy of H2-phthalocyanine.

We report on a combined experimental and theoretical carbon and nitrogen K-edge near-edge x-ray absorption fine structure investigation on condensed metal-free phthalocyanine (H2Pc). Based on the results from improved virtual orbital calculations, all resonances in the experimental high-resolution data can be assigned to various electronic transitions. The comparison between experiments and calculations further shows that a significant influence of the core hole, which affects both the transition energies and the cross sections, is present and must be considered in theoretical approaches. Moreover, additional fine structure is clearly resolved for the first N 1s-->pi* transition, which can be interpreted as vibronic coupling to the electronic core excitation.