In:
The Journal of Chemical Physics, AIP Publishing, Vol. 122, No. 12 ( 2005-03-22)
Abstract:
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 288eV photon energy, due to absorption to π* virtual orbitals, and broader structures at higher energy, involving σ* virtual orbitals. The sharp absorption structures to the π* 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 π* symmetry, from the six chemically shifted C 1s core orbitals.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
2005
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
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