A UHV-STM/STS Study of Electronic Structures of[Ni3(dpa)4(NCS)2] and [Ni11(bnatpya)4(NCS)2](PF6)4

Autor: Shang-Shu Lin, 林上書
Rok vydání: 2017
Druh dokumentu: 學位論文 ; thesis
Popis: 105
This study discuss the arrangement and electricity of two one-dimensional metal string molecules [Ni3(dpa)4(NCS)2] and [Ni11(bnatpya)4(NCS)2]4+ which are different lengths on the Au(111) surface. Sample preparation and surface analysis were obtained by ultrahigh vacuum scanning tunneling microscope (UHV-STM). The samples were prepared by dissolving the metal string molecular with the CH2Cl2 solvent, then drop on the surface of Au(111) and obtaining the [Ni3(dpa)4(NCS)2]/Au(111) and [Ni11(bnatpya)4(NCS)2]4+/Au(111). In the first part, the STM image shows that [Ni3(dpa)4(NCS)2] is adsorbed on the step edge of Au(111) surface, and the height of single metal string molecule could obtained from the height profile. The dI/dV spectra of [Ni3(dpa)4(NCS)2] on Au(111) revealed two characteristic peaks, −0.65 eV and −0.10 eV by the scanning tunneling spectroscopy (STS) .To make sure the molecular characteristics from the image, using the longer molecules of [Ni11(bnatpya)4(NCS)2]4+ to drop on the surface, and the STM image shows the molecules are disorderly and distributed on the surface with one or more repeating monomers by the coffee ring effect. The dI/dV spectrum on the cluster and the single molecule, respectively, the results show that the cluster has a broad peak at the negative bias. In the second part, the chamber is cooled to 78 K to reduce the influence of the thermal disturbance of the molecule and the tip. From the STM images, the electron cloud of single metal string molecule exhibits a left-handed and right-handed configuration with an angle of about 50o between the metal axis and the helical electron cloud. In addition, it is observed that the electron cloud of some molecules reveal non-left and right hand but rather about 90o with the metal axis.
Databáze: Networked Digital Library of Theses & Dissertations
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