Study of inelastic tunneling excitation of a single molecule and a single atom on surfaces by using scanning tunneling microscope and atomic force microscope

Abstract

The ultimate miniaturization of a device can be realized by making a single atom or single molecular device. To achieve this, it is essential to study the fundamental properties of single atoms and single molecules on surfaces. In this thesis, I studied the properties of a single vanadyl phthalocyanine molecule and Fe atom on surfaces using a scanning tunneling microscope and atomic force microscope. The mechanism of the hopping excitation of hydrogen in the tunneling junction was identified, and its excitation spectroscopy was applied to measure the intermolecular interaction between vanadyl phthalocyanine and hydrogen. Through this, interactions between molecules at the atomic scale were measured and high-resolution atomic force microscopic images were obtained using hydrogen. Moreover, in case of Fe, the dependence of the electrical and magnetic properties of Fe single atom on the absorption site on insulating NaCl layer was studied using spin-excitation spectroscopy. Through this, it was found that the electronic configuration of Fe atom embedded in the soft NaCl layer and the magnetic properties according to it were different from those known previously. In the theoretical part, the excitation energy of hydrogen and iron could be calculated through the density functional theory calculation, and the results were consistent with the inelastic electron tunneling spectroscopy results.