Investigation Of Electronic Characteristics In Low Dimensional Systems

With the development of quantum physics,the research of low-dimensional nanomaterials has attracted great attention in the last few years.Low-dimensional materials have unique electronic features which are different from three-dimensional materials.Studying the behavior of electrons with sub-nano scale helps us to observe and discover its properties in essenceScanning tunneling microscopy?STM?has ultra-high spatial resolution of sub?nanometers and been sensitive to surface local density of states?LDOS?.It can study electronic states density of sample surface and atoms or molecules adsorbed on surface It can further analyze the characteristics of electron-plasmon,electron-electron,and electron-molecular orbital interactions in the system.Raman spectroscopy is sensitive to the lattice structure and defects of materials,and can study the mechanism of electron-phonon interaction in the systemIn this paper,we studied the Raman modes of MoSe₂ by Raman spectroscopy.And we reported electroluminescence process of Ag?1 11?surface,the structure and electronic states density of Ti₂O₃ on TiO₂?1 10?surface,and inelastic tunneling spectrum of single water molecules on the surface of copper nitride?Cu₂N?.The details are summarized as follows1.We investigate the Raman spectroscopy of MoSe₂.Evolution of monolayer MoSe₂ Raman mode under external pressure up to 5.73 GPa.The double resonance Raman mode 2ZA is observed in Raman spectroscopy near 250 cm-1,which presents pronounced intensity with pressure dependence and is derived from the electron-phonon interaction.Significant variation in 2ZA peak intensity under different pressures reflects the change in electronic band structure as pressure varies,which is consistent with the blue shift in PL spectroscopy.The pressure-sensitive Raman scattering phenomenon provides new materials for the development of two-dimensional material sensors2.We studied that scanning tunneling microscopy luminescence?STML?in Ag Tip-Ag?111?sample tunnel junction with changing tunneling current and sample bias The spectral intensity is linear with the tunneling current,indicating that STML is one electron behavior.In the field emission region,the spectral intensity oscillates with the sample bias,and there is a maximum value at V=?E_n+hv?/e The maximum value increases with increasing En,which may result from the electromagnetic field of the nanoparticles in the tunnel junction and the density of state of the field emission level.3.We measured the configuration and LDOS of Ti₂O₃ restructure on the TiO₂?110?surface.Ti₂O₃ is a double-line structure formed by Ti3+interstitial atoms and oxygen atoms on surface.The LDOS density oscillates along the chain.In order to understand the characteristics of electronic states,we consider the one-dimensional quantum well model,with periodic potential field by internal atomic periodic crystal and the Coulomb potential field of the charge at both ends of the restructure.We discussed the effect of LDOS on the band gap of Ti₂O₃ with different lengths.4.We investigated that configuration and vibrational spectrum of water molecules adsorbed on Cu₂N surface.Inelastic tunneling spectrum?IETS?of a single water was measured with functional tip adsorbing a water molecule and tip-water coupling interaction.The vibrational energy of the water is highly sensitive to the surface and the height of tunnel junction.