The Effect Of Ion And Concentration Controlling On Single Molecular Conductance

In recent decades,molecular electronics has been the focus because of its potential application in the future electronic device.Up to now,the key is to build molecular junction and measure its properties.There are a lot of factors,which may influence the effecting molecular conductance,such as contact configuration,anchoring group,the surrounding environment and molecular structure.However,there is still many factors need to be further carried out in this area.Here,we mainly study the influence of ion and concentration on single molecular conductance.Scanning tunneling microscope-break junction(STM-BJ)method was used to explore the influence of ion on the molecular conductance,the result illustrates that different ion can change the molecular conductance.When we study the effect of concentration on single molecular conductance,electrochemical jump-to-contact scanning tunneling microscope-break junction(EC-STM)method was used to carried out the experiment,the results found that ion concentration can also effect the molecular conductance.The main work of this paper is as follow:1.The influence of ion on 15-crown-5 was carried out by using Au as electrode,and the result shows that the single molecular conductance of 15-crown-5 would became large upon the coordinating of positive ion.Moreover,the single molecular conductance depends on the ion species,and has relation to the radius of ion,which may change the interaction configuration between ion and molecule.2.We have also measured the conductance of 18-crown-6 and 12-crown-4 in different ion solution.Similar behavior of conductance dependence on the coordination of ion was found,however,there is small difference among the different ion species.3.The influence of ion on the crown ether,which is on the backbone of molecule,was studied.The result shows that conductance became very large with the interaction of ion,which may be caused by the change of molecular configuration upon the interaction with ion.4.Taking terephthalaldehyde and terephthalic acid as target molecules,we have measured the single molecular conductance of terephthalaldehyde and terephthalic acid in different Cu ion concentration solution,while Au(111)and Cu wire were used as work and reference electrodes,respectively.It was found that the single molecular conductance is dependence on the Cu ion concentration,which is contributed to the changing of electrode potential caused by the varying of concentration.This work demonstrates that the ion can play an important role in changing molecular conductance in a special way.