We present the design and performance of a home-built scanning tunneling microscope （STM）, which is compact （66 mm tall and 25 mm in diameter）, yet equipped with a 3D atomic precision piezoelectric motor in which ...We present the design and performance of a home-built scanning tunneling microscope （STM）, which is compact （66 mm tall and 25 mm in diameter）, yet equipped with a 3D atomic precision piezoelectric motor in which the Z coarse approach relies on a high simplic-ity friction-type walker （of our own invention） driven by an axially cut piezoelectric tube. The walker is vertically inserted in a piezoelectric scanner tube （PST） with its brim laying at on the PST end as the inertial slider （driven by the PST） for the XZ （sample plane） motion. The STM is designed to be capable of searching rare microscopic targets （defects, dopants, boundaries, nano-devices, etc.） in a macroscopic sample area （square millimeters） under extreme conditions （low temperatures, strong magnetic elds, etc.） in which it ts. It gives good atomic resolution images after scanning a highly oriented pyrolytic graphite sample in air at room temperature.展开更多
AIM： To evaluate the clinical impact of multidetector computed tomography （MDCT） before double-balloon endoscopy （DBE） for patients with obscure gastrointestinal bleeding （OGIB）.
The reconstructed structures of Cu（100） surface induced by O2 dissociative adsorption were investigated by low energy electron diffraction and scanning tunneling microscopy. At lower oxygen coverage, it was found th...The reconstructed structures of Cu（100） surface induced by O2 dissociative adsorption were investigated by low energy electron diffraction and scanning tunneling microscopy. At lower oxygen coverage, it was found that two reconstructed structures, i.e. c（2×2）-O and （√2×2√2）R45°-O are coexistent. The domain size of the c（2×2）-O structure decreased with the increasing of O2 exposure. The reconstructed structure at very small coverage was also investigated and a “zigzag” structure was observed at this stage. The “zigzag” structure was identified as boundaries of local c（2×2） domains. It was found that the strip region shows much stronger molecule-substrate interaction than that of oxygen covered regions, making it a proper template for patterned organic films. The sequence of the thermal stability was found as zigzag structure〉c（2×2）〉（√2×2√2）R45°-O.展开更多
Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anch...Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anchored on the Au（111） surface to efficiently collect and pin hydrogen molecules. A two-dimensional （2D） molecular hydrogen cluster is formed around the MnPc. The hydrogen cluster exhibits bias-dependent topography and spatial-dependent conductance spectra, which are rationalized by the exponentially decreasing threshold energy with distance from the central MnPc to activate the motion of the H2 molecules. This exponential drop reveals an interfacial phase behavior in the 2D cluster.展开更多
文摘We present the design and performance of a home-built scanning tunneling microscope （STM）, which is compact （66 mm tall and 25 mm in diameter）, yet equipped with a 3D atomic precision piezoelectric motor in which the Z coarse approach relies on a high simplic-ity friction-type walker （of our own invention） driven by an axially cut piezoelectric tube. The walker is vertically inserted in a piezoelectric scanner tube （PST） with its brim laying at on the PST end as the inertial slider （driven by the PST） for the XZ （sample plane） motion. The STM is designed to be capable of searching rare microscopic targets （defects, dopants, boundaries, nano-devices, etc.） in a macroscopic sample area （square millimeters） under extreme conditions （low temperatures, strong magnetic elds, etc.） in which it ts. It gives good atomic resolution images after scanning a highly oriented pyrolytic graphite sample in air at room temperature.
文摘AIM： To evaluate the clinical impact of multidetector computed tomography （MDCT） before double-balloon endoscopy （DBE） for patients with obscure gastrointestinal bleeding （OGIB）.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China （No.60506019）.
文摘The reconstructed structures of Cu（100） surface induced by O2 dissociative adsorption were investigated by low energy electron diffraction and scanning tunneling microscopy. At lower oxygen coverage, it was found that two reconstructed structures, i.e. c（2×2）-O and （√2×2√2）R45°-O are coexistent. The domain size of the c（2×2）-O structure decreased with the increasing of O2 exposure. The reconstructed structure at very small coverage was also investigated and a “zigzag” structure was observed at this stage. The “zigzag” structure was identified as boundaries of local c（2×2） domains. It was found that the strip region shows much stronger molecule-substrate interaction than that of oxygen covered regions, making it a proper template for patterned organic films. The sequence of the thermal stability was found as zigzag structure〉c（2×2）〉（√2×2√2）R45°-O.
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 51210003 and 11290165）, National Basic Research Program of China （No. 2009CB929103）, TRR61 and Chinese Academy of Sciences.
文摘Low-dimensional H2 aggregates have been successfully fabricated on Au（111） surfaces and investigated by means of low temperature scanning tunneling microscopy. We use manganese phthalocyanine （MnPc） molecules anchored on the Au（111） surface to efficiently collect and pin hydrogen molecules. A two-dimensional （2D） molecular hydrogen cluster is formed around the MnPc. The hydrogen cluster exhibits bias-dependent topography and spatial-dependent conductance spectra, which are rationalized by the exponentially decreasing threshold energy with distance from the central MnPc to activate the motion of the H2 molecules. This exponential drop reveals an interfacial phase behavior in the 2D cluster.
