2:45 PM - 3:00 PM
▲ [14p-A32-7] Investigation of Density of States and Local Contact Potential Difference on Rutile TiO2(110) by STM/KPFM
Keywords:TiO2(110), density of states, contact potential difference
Au nanoclusters supported on TiO2(110) surface has been extensively used to investigate the mechanism of the CO oxidation reaction since it has extremely high catalytic reactivity [1]. On TiO2 surface, defects significantly play an important role in the adsorption of Au nanoclusters and catalytic reaction process [2]. However, the reaction processes, the mechanism of O2 dissociation and reactive site etc., haven’t been clarified yet. To clarify the above questions, the measurement of local contact potential difference (LCPD) with atomic resolution on TiO2(110) surface are necessary. In this study, we propose a method of simultaneously measurement of density of states and the LCPD on TiO2(110) surface with atomic resolution by scanning tunneling microscopy (STM) and Kelvin probe force microscopy (KPFM).
In the experiment, the method of FM-KPFM without bias voltage feedback was performed [3] at the constant height mode to remove the crosstalk of the surface topography. The DC bias added with ac bias voltage was applied between the tip and sample. The frequency shift was measured by phase locked loop (PLL). Two lock-in amplifiers were used to measure frequency shift at fω and f2ω. The LCPD signals were numerically calculated from the divided results of the fω and f2ω signals. As a result, the LCPD image with atomic resolution and local density of states image were observed simultaneously. To discuss the effect of surface defects to the distribution of the surface potential and local density of states, spectroscopies were also investigated.
In the experiment, the method of FM-KPFM without bias voltage feedback was performed [3] at the constant height mode to remove the crosstalk of the surface topography. The DC bias added with ac bias voltage was applied between the tip and sample. The frequency shift was measured by phase locked loop (PLL). Two lock-in amplifiers were used to measure frequency shift at fω and f2ω. The LCPD signals were numerically calculated from the divided results of the fω and f2ω signals. As a result, the LCPD image with atomic resolution and local density of states image were observed simultaneously. To discuss the effect of surface defects to the distribution of the surface potential and local density of states, spectroscopies were also investigated.