Inversed linear dichroism in F K-edge NEXAFS spectra of fluorinated planar aromatic molecules.

Physical Review B 86, 075469 (2012)

Inversed linear dichroism in F K-edge NEXAFS spectra of fluorinated planar aromatic molecules.

D. G. de Oteyza, A. Sakko, A. El-Sayed, E. Goiri, L. Floreano, A. Cossaro, J. M. García-Lastra, A. Rubio, J. E. Ortega

The symmetry and energy distribution of unoccupied molecular orbitals is addressed in this work by means of NEXAFS and DFT calculations for planar, fluorinated organic semiconductors (perfluorinated copper-phtalocyanines and perfluoropentacene). We demonstrate how molecular orbitals with significant density of states on the flurine atoms show different symmetry from those mainly located on C and N atoms. As a result, the angle dependent linear dichroism in NEXAFS F K-edge spectra is inversed with respect to that in the C and N K-edges. In addition, the significant overlap in energy of pi* and sigma* orbitals throughout the F K-edge spectrum hampers its use for analysis of molecular orientations from angle dependent NEXAFS measurements.

Additional Information

Download
Preprint - 608.33 KB
Doi
http://dx.doi.org/10.1103/PhysRevB.86.075469

Related Research Areas