11:15 〜 11:30
▼ [18a-C310-7] Charge State Dependence of Oxygen Adatom Conductance Switching on Rutile TiO2(110) by nc-AFM/STM at 78 K
キーワード：conductance switching, charge state, nc-AFM/STM
Background] Conductance property of the individual atom can exclusively determine the charge transferring rate, [1, 2] which plays a key role in determining the catalytic efficiency of the catalytic reactions. Therefore, the precise characterization and deliberate switching of the atom conductance become significantly important in clarifying and controlling the catalytic reactions based on homogeneous catalyst.
[Experimental method] In our experiment, a home-built combined noncontact atomic force microscopy (nc-AFM) and scanning tunneling microscopy (STM) was used to investigate the dependence of the oxygen adatom (Oad) conductance switching on its charge states under ultrahigh vacuum conditions (base pressure below 5 × 10-11 Torr) at 78 K. The nc-AFM was operated in a frequency-modulation mode with an iridium-coated Si cantilever used as a sensor with small oscillation amplitude (5 Å). A bias voltage was applied to the sample. The oxygen gas (0.1 L, high purity of 99.9 %) was exposed to clean sample at room temperature.
[Experimental results and discussion] We firstly clarify the Oad charge states on rutile TiO2(110) using simultaneous nc-AFM/STM measurement (Figure 1a and 1b), which is in line with our previous work [3]. Secondly, we experimentally demonstrate that the Oad- shows much higher conductance than Oad2-, and the Oad conductance switching, hysteresis and coupling can be obtained by deliberately manipulating the Oad charge states through ramping the bias voltage (Figure 1c and 1d), which is attributed to the tunneling electrons injection from the tip into the manipulated species or from the manipulated species to the substrate polaron. Our study provides a good reference for the systematic investigation of the atomic conductance and potentially has an overriding effect on revolutionizing the investigation of the catalytic reactions.
[Experimental method] In our experiment, a home-built combined noncontact atomic force microscopy (nc-AFM) and scanning tunneling microscopy (STM) was used to investigate the dependence of the oxygen adatom (Oad) conductance switching on its charge states under ultrahigh vacuum conditions (base pressure below 5 × 10-11 Torr) at 78 K. The nc-AFM was operated in a frequency-modulation mode with an iridium-coated Si cantilever used as a sensor with small oscillation amplitude (5 Å). A bias voltage was applied to the sample. The oxygen gas (0.1 L, high purity of 99.9 %) was exposed to clean sample at room temperature.
[Experimental results and discussion] We firstly clarify the Oad charge states on rutile TiO2(110) using simultaneous nc-AFM/STM measurement (Figure 1a and 1b), which is in line with our previous work [3]. Secondly, we experimentally demonstrate that the Oad- shows much higher conductance than Oad2-, and the Oad conductance switching, hysteresis and coupling can be obtained by deliberately manipulating the Oad charge states through ramping the bias voltage (Figure 1c and 1d), which is attributed to the tunneling electrons injection from the tip into the manipulated species or from the manipulated species to the substrate polaron. Our study provides a good reference for the systematic investigation of the atomic conductance and potentially has an overriding effect on revolutionizing the investigation of the catalytic reactions.