This article is cited in 24 papers

Atoms, Spectra, and Radiation

Spectroscopic states of PTCDA negative ions and their relation to the maxima of unoccupied state density in the conduction band

S. A. Pshenichnyuk^a, A. V. Kukhta^b, I. N. Kukhto^b, A. S. Komolov<sup>c

a</sup> Institute of Molecule and Crystal Physics, Ufa Federal Research Centre, Russian Academy of Sciences
^b B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk
^c Saint Petersburg State University

Abstract: Electron attachment spectroscopy is employed to demonstrate that the scattering of slow (0–15 eV) electrons from perylenetetracarboxilic dianhydride (PTCDA) molecules in the gas phase leads to the resonant formation of molecular and fragment negative ions detected in the mass-spectrometric experiment. Depending on the electron energy, currents of anions have clearly manifested peaks at 0.14, 1.9, 3.0, 4.8, and 5.7 eV. In addition, resonant states are also detected at thermal energy (0 eV) of scattered electrons, as well as at 0.4 and 1.0 eV, as shoulders on experimental curves. The spectroscopic states of PTCDA anions at energies exceeding 0 eV are interpreted in terms of the formation of shape resonances on the basis of calculated values of energies of $\pi^*$-type unoccupied molecular orbitals. It is found that the positions of unoccupied orbitals of an isolated PTCDA molecule correspond to the peaks in the density of states of the conduction band of PTCDA films provided that the energies of the orbitals are shifted by 1.4 eV. The latter value can be interpreted as the binding energy of a molecule in the film due to the polarization interaction with the surroundings.

Received: 21.07.2010

 English version: Technical Physics, 2011, 56:6, 754–759

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