Electronic Properties and Orbital-Filling Mechanism in Rb-Intercalated Copper Phthalocyanine

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• 作者：F. Evangelista ; R. Gotter ; N. Mahne ; S. Nannarone ; A. Ruocco ; P. Rudolf
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：April 24, 2008
• 年：2008
• 卷：112
• 期：16
• 页码：6509 - 6514
• 全文大小：108K
• 年卷期：v.112,no.16(April 24, 2008)
• ISSN：1932-7455

文摘

The evolution of the electronic properties of a thin film of copper phthalocyanine deposited on Al(100) andprogressively intercalated with rubidium atoms was followed by photoemission and X-ray absorptionspectroscopies. Electron donation from the Rb atoms to the C₃₂H₁₆N₈Cu molecules results in the lifting of thedegeneracy in the e_g ligand-derived molecular orbital and the lowering of the molecular symmetry. ForRb_~2C₃₂H₁₆N₈Cu, spectral evidence indicates that both donated electrons reside in the first split-off e_g-derivedlevel, thus creating an electronic inequivalence between the C atoms in the benzene rings. For higher Rbconcentrations, a reduction of the Cu oxidation state is observed, together with a new Cu-derived state invalence-band photoemission spectra, testifying to the filling of the b_1g orbital. Thus, even though b_1g is thelowest unoccupied orbital of the neutral molecule, in the film, the Cu-derived b_1g-derived states are occupiedonly after a partial filling of the e_g-derived band has taken place. Despite the fact that the e_g-derived spectralweight becomes larger as the rubidium content in the Rb_xC₃₂H₁₆N₈Cu compound increases, no spectral densitywas observed at the Fermi level, showing that the film remains insulating for all of the investigatedstoichiometries.