We report an electrochemically assisted mechanically controllable break junction （EC-MCBJ） approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by e...We report an electrochemically assisted mechanically controllable break junction （EC-MCBJ） approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by electrochemical deposition and then mounted on a homebuilt MCBJ platform. A large number of Au- molecule-Au junctions were produced sequentially by repeated breaking and reconnecting of the gold nanobridge. In order to measure their single molecule conductance, statistical conductance histograms were generated for benzene-l,4-dithiol （BDT） and 4,4＇-bipyridine （BPY）. The values extracted from these histograms were found to be in the same range as values previously reported in the literature. Our method is distinct from the ones used to acquire these previously reported literature values, however, in that it is faster, simpler, more cost-effective, and changing the electrode material is more convenient.展开更多
This study analyzes the optimal transfer trajectory of a spacecraft propelled by a spinstabilized electric solar wind sail(E-sail)with a single conducting tether and a spin axis with a fixed direction in an inertial(h...This study analyzes the optimal transfer trajectory of a spacecraft propelled by a spinstabilized electric solar wind sail(E-sail)with a single conducting tether and a spin axis with a fixed direction in an inertial(heliocentric)reference frame.The approach proposed in this study is useful for rapidly analyzing the optimal transfer trajectories of the current generation of small spacecraft designed to obtain in-situ evidence of the E-sail propulsion concept.In this context,starting with the recently proposed thrust model for a single-tether E-sail,this study discusses the optimal control law and performance in a typical two-dimensional interplanetary transfer by considering the(binary)state of the onboard electron emitter as the single control parameter.The resulting spacecraft heliocentric trajectory is a succession of Keplerian arcs alternated with propelled arcs,that is,the phases in which the electron emitter is switched on.In particular,numerical simulations demonstrated that a single-tether E-sail with an inertially fixed spin axis can perform a classical mission scenario as a circle-to-circle two-dimensional transfer by suitably varying a single control parameter.展开更多
文摘We report an electrochemically assisted mechanically controllable break junction （EC-MCBJ） approach to investigating single molecule conductance. Electrode pairs connected with a gold nanobridge were fabricated by electrochemical deposition and then mounted on a homebuilt MCBJ platform. A large number of Au- molecule-Au junctions were produced sequentially by repeated breaking and reconnecting of the gold nanobridge. In order to measure their single molecule conductance, statistical conductance histograms were generated for benzene-l,4-dithiol （BDT） and 4,4＇-bipyridine （BPY）. The values extracted from these histograms were found to be in the same range as values previously reported in the literature. Our method is distinct from the ones used to acquire these previously reported literature values, however, in that it is faster, simpler, more cost-effective, and changing the electrode material is more convenient.
文摘This study analyzes the optimal transfer trajectory of a spacecraft propelled by a spinstabilized electric solar wind sail(E-sail)with a single conducting tether and a spin axis with a fixed direction in an inertial(heliocentric)reference frame.The approach proposed in this study is useful for rapidly analyzing the optimal transfer trajectories of the current generation of small spacecraft designed to obtain in-situ evidence of the E-sail propulsion concept.In this context,starting with the recently proposed thrust model for a single-tether E-sail,this study discusses the optimal control law and performance in a typical two-dimensional interplanetary transfer by considering the(binary)state of the onboard electron emitter as the single control parameter.The resulting spacecraft heliocentric trajectory is a succession of Keplerian arcs alternated with propelled arcs,that is,the phases in which the electron emitter is switched on.In particular,numerical simulations demonstrated that a single-tether E-sail with an inertially fixed spin axis can perform a classical mission scenario as a circle-to-circle two-dimensional transfer by suitably varying a single control parameter.
