The inelastic electron tunneling spectroscopy(IETS) of four edge-modified finite-size grapheme nanoribbon(GNR)-based molecular devices has been studied by using the density functional theory and Green's function method. The effects of atomic structures and connection types on inelastic transport properties of the junctions have been studied. The IETS is sensitive to the electrode connection types and modification types. Comparing with the pure hydrogen edge passivation systems, we conclude that the IETS for the lower energy region increases obviously when using donor–acceptor functional groups as the edge modification types of the central scattering area. When using donor–acceptor as the electrode connection groups, the intensity of IETS increases several orders of magnitude than that of the pure ones. The effects of temperature on the inelastic electron tunneling spectroscopy also have been discussed. The IETS curves show significant fine structures at lower temperatures. With the increasing of temperature, peak broadening covers many fine structures of the IETS curves.The changes of IETS in the low-frequency region are caused by the introduction of the donor–acceptor groups and the population distribution of thermal particles. The effect of Fermi distribution on the tunneling current is persistent.
Mg-doped ZnO (Mg_xZn_(1-x)O, x=0-0.10)nanoparticles were prepared by sol-gel method. Structural characterization by X-ray diffraction (XRD) indicates that the lattice parameter a increases and c decreases linearly with the increase in Mg content (x) due to the substitution of Mg^(2+) for Zn^(2+) in ZnO lattice. The blueshift of Raman modes is observed, impling the increase in force constant of atom vibration in the Mg_xZn_(1-x)O (MgZnO) nanoparticles. Resonant Raman spectra show longitudinal optical phonon overtones up to fifth order, revealing that the short part of the electron-phonon interaction is enhanced and long-range part is weakened by Mg doping.
Zhonglyu JiangKe-Rong ZhuZhong-Qing LinShao-Wei JinGuang Li
