AVS 53rd International Symposium
    Surface Science Wednesday Sessions
       Session SS2+EM-WeA

Paper SS2+EM-WeA4
Resonant Soft X-Ray Emission and Resonant Inelastic X-Ray Scattering: New Probes of Electronic Structure in Organic Semiconductors

Wednesday, November 15, 2006, 3:00 pm, Room 2004

Session: Organic Film Growth and Characterization
Presenter: K.E. Smith, Boston University
Authors: Y. Zhang, Boston University
J.E. Downes, Macquarie University, Australia
A. DeMasi, Boston University
A. Matsuura, AFOSR
C. McGuinness, Trinity College Dublin, Ireland
P.A. Glans, Boston University
T. Learmonth, Boston University
S. Wang, Boston University
L. Plucinski, Boston University
K.E. Smith, Boston University
Correspondent: Click to Email
We report the use of synchrotron radiation-excited resonant soft x-ray emission spectroscopy (XES) and resonant inelastic x-ray scattering (RIXS) to study the electronic structure of thin film organic semiconductors.@footnote 1@ XES directly measures the element-specific partial density of states (PDOS) in materials. When excited at a core level absorption threshold, RIXS features can be observed in the spectra, which are related to low energy excitations. The materials studied to date include a selection of metal phthalocyanines (Cu-Pc, FCuPc, VO-PC, TiO-Pc, Ni-Pc), as well as other organic semiconductor materials such as Alq3 and QAD. Our results are in excellent agreement with theory, but differ significantly from previously published results. The films were found to be highly susceptible to radiation damage. We demonstrate the ability to accurately measure states near E@sub F@, and show that previously published XES studies of organic semiconductors are dominated by beam damage effects. This application of resonant XES has important consequences for the determination of band gap energies in organic molecular systems, since it allows determination of the non-ionized electronic structure. Supported in part by the U.S. AFOSR under FA9550-06-1-0157, by the Petroleum Research Fund, and by NSF under DMR-0304960. The spectrometer system is funded by the U.S. ARO under DAAD19-01-1-0364 and DAAH04-95-0014. Experiments were performed at the NSLS which is supported by the U.S. DOE, Divisions of Materials and Chemical Sciences. @FootnoteText@ @footnote 1@ Y. Zhang, S. Wang, T. Learmonth, L. Plucinski, A.Y. Matsuura, S. Bernardis, C. O'Donnell, J.E. Downes, and K.E. Smith, Chem. Phys. Lett. 413, 95 (2005); J.E. Downes, C. McGuinness, P.A. Glans, T. Learmonth, D. Fu, P. Sheridan, and K.E. Smith, Chem. Phys. Lett. 390, 203 (2004).