Core-level spectra and molecular deformation in adsorption: V-shaped pentacene on Al(001)

Beilstein Journal of Nanotechnology

Luca Floreano¹  Guido Fratesi²  He Lin²  Gian Paolo Brivio²  Anu Baby² 

[1] CNR-IOM, Laboratorio TASC, Basovizza SS-14, Km 163.5, I-34149 Trieste, Italy;ETSF, CNISM, Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 55, I-20125 Milano, Italy;

关键词: aluminum;    density functional theory (DFT);    near-edge X-ray absorption fine structure (NEXAFS);    pentacene;    X-ray photoelectron spectroscopy (XPS);   

DOI  :  10.3762/bjnano.6.230

来源: DOAJ

【 摘 要 】

By first-principle simulations we study the effects of molecular deformation on the electronic and spectroscopic properties as it occurs for pentacene adsorbed on the most stable site of Al(001). The rationale for the particular V-shaped deformed structure is discussed and understood. The molecule–surface bond is made evident by mapping the charge redistribution. Upon X-ray photoelectron spectroscopy (XPS) from the molecule, the bond with the surface is destabilized by the electron density rearrangement to screen the core hole. This destabilization depends on the ionized carbon atom, inducing a narrowing of the XPS spectrum with respect to the molecules adsorbed hypothetically undistorted, in full agreement to experiments. When looking instead at the near-edge X-ray absorption fine structure (NEXAFS) spectra, individual contributions from the non-equivalent C atoms provide evidence of the molecular orbital filling, hybridization, and interchange induced by distortion. The alteration of the C–C bond lengths due to the V-shaped bending decreases by a factor of two the azimuthal dichroism of NEXAFS spectra, i.e., the energy splitting of the sigma resonances measured along the two in-plane molecular axes.

【 授权许可】

Unknown