Research of Monolayer/Metal Interface by Inelastic Electron Tunneling Spectroscopy (IETS)

本研究的目的是研究金属/LB膜的界面，即LB膜如何吸附在金属（氧化物）表面。我们建立了非弹性电子隧穿谱（IETS）测量系统，通过该系统可以观测到金属-绝缘体-金属隧道结中金属（氧化物）的声子和分子振动峰.我们制备了Sn、Pb薄膜作为LB膜转移的基底，分别采用两种氧化方法（即氧化法和氧化法）制备了Sn/SnO_2/Pb、Pb/PbO /Pb。G.通过改变湿度条件）。我们还观察到了Sn、Pb氧化物的声子谱。我们做这个实验的原因是为了掌握LB膜转移所需的金属表面条件。从这些测量中，我们获得了以下结果。(1)PbO声子的轮廓不随湿度变化。即使有机分子掺杂到金属/金属氧化物界面中，也没有观察到分子振动峰。(2)湿度对SnO_2声子的影响很大。在高偏压区观察到分子振动峰，因此我们用Sn作为隧道结的基电极，观察LB单层膜的分子振动峰。在此基础上，我们制备了Sn/SnO_2/Ar_2Co/Pb隧道结，并观察了隧道谱。通过对超导Pb能隙的测量，我们认识到在这种隧道结中电子的转移主要是隧穿。进一步测量了高偏压区的隧道谱。结果表明，在相同的隧道结中观察到了“游程相关”的隧道谱。这可能是由于通过组分的排列增强LB单层的永久偶极子的充电。

The aim of this research is to study a metal/LB monolayer interface, that is, to know how a LB monolayer would be adsorbed on a metal (oxide).The results we researched are as follows ;1. We constructed Inelastic Electron Tunneling Spectroscopy (IETS) measuring system, by which we can observe metal (oxide) phonon and molecular vibration peaks in a metal-insulator- metal tunnel jonction.2. We prepared Sn, Pb thin films, that would be used as substrates on which a LB monolayer could be transfered, Sn/SnO_2/Pb, Pb/PbO /Pb produced by two kinds of oxidation procedures (e. g. by varying humidity condition). And we observed Sn, Pb oxide phonon spectra. The reason why we did this experiments is to grasp the surface condition of the metals for a LB monolayer to be transfered. From these measurements, we obtained results below.(1) The contours of PbO phonons do not change with humidity condition. The molecular vibration peaks are not observed, even if organic molecules are doped into the metal/metal oxide interface.(2) SnO_2 phonons are strongly affected by humidity condition. And in the higher bias region the molecular vibration peaks are observed.Therefore we used Sn as the base electrode of a tunnel junction to observe molecular vibration peaks of LB monolayer. From the experimental results above mentioned, we prepared Sn/SnO_2/Ar_2Co/Pb tunnel junctions, and observed the tunnel spectra. We recognized that tunneling is the dominant electron transfer in this tunnel junction from the measurement of supercnducting Pb energy gap. Further we measured the tunnel spectra in the higher bias region. As the result, 'run-dependent' tunnel spectra were observed in the same tunnel junction. This would probably be attributed to the charging with enhancement of permanent dipole of a LB monolayer by alignment of the constituents.