Core-shell photoabsorption and photoelectron spectra of gas-phase pentacene: Experiment and theory
2005 (English)In: Journal of chemical physics Online, ISSN 1089-7690 (print), 0021-9606 (online), Vol. 122, no 12, 124305- p.Article in journal (Refereed) Published
The C K-edge photoabsorption and 1s core-level photoemission of pentacene (C22H14) free molecules are experimentally measured, and calculated by self-consistent-field and static-exchange approximation ab initio methods. Six nonequivalent C atoms present in the molecule contribute to the C 1s photoemission spectrum. The complex near-edge structures of the carbon K-edge absorption spectrum present two main groups of discrete transitions between 283 and 288 eV photon energy, due to absorption to * virtual orbitals, and broader structures at higher energy, involving * virtual orbitals. The sharp absorption structures to the * empty orbitals lay well below the thresholds for the C 1s ionizations, caused by strong excitonic and localization effects. We can definitely explain the C K-edge absorption spectrum as due to both final (virtual) and initial (core) orbital effects, mainly involving excitations to the two lowest-unoccupied molecular orbitals of * symmetry, from the six chemically shifted C 1s core orbitals. ©2005 American Institute of Physics
Place, publisher, year, edition, pages
2005. Vol. 122, no 12, 124305- p.
organic compounds, photoexcitation, photoelectron spectra, SCF calculations, ab initio calculations, chemical shift, molecular electronic states, molecule-photon collisions
IdentifiersURN: urn:nbn:se:liu:diva-12685DOI: 10.1063/1.1864852OAI: oai:DiVA.org:liu-12685DiVA: diva2:16859