EVALUATION OF MOLECULAR ORGANIC MONOLAYER BY SPACIAL RESOLVED INELASTIC ELECTRON TUNNELING SPECTROSCOPY

为了获得基于配备STM针尖的IETS测量系统的高密度记录系统的基本信息，我们通过施加电压脉冲来研究LB膜的IETS的变化。实验中使用了欧米茄-三十碳烯酸(omega-tricosenoic acid，omegaT)和二乙炔单体(DA)的LB膜。由于omegaT和DA可以分别在电子束和紫外光照射下聚合，因此这些薄膜的化学反应可以通过电压脉冲进行预期。主要研究结果如下：1)施加电压脉冲后，大部分的IETS峰出现幅度变化和峰位移位。2)IETS和FT-IR-RAS的变化表明，观察到的IETS变化仅限于隧道电流集中的局部区域。3)由于电压脉冲引起的聚合和其他化学反应，omegaT LB膜的IETS的变化。4)通过施加-20V的负电压脉冲，可逆地修正了DA膜中正电压脉冲诱导的LET变化。这一结果对可重写存储系统具有吸引力。

Inorder to obtain the basic information for high-density recording system based on IETS measurement system equiped with STM tip, we have investigated the change of IETS of Langmuir-Blodgett (LB) films by applying a voltage pulse. In the experiment, LB films of omega-tricosenoic acid (omegaT) and diacetylene monomer (DA) were employed. The chemical reactions of these films are expected by the voltage pulse because omegaT and DA can be polymerized by electron beam and UV light exposure, respectively. Main results are summarized below.1) Most of IETS peaks show amplitude changes and peak shifts by applying voltage pulse.2) The changes in IETS and FT-IR-RAS indicate that the change obserbed in IETS is restricted in local area where the tunneling current concentrates.3) The changes of IETS of omegaT LB films are due to the polymerization and other chemical reactions induced by the voltage pulse.4) The LETS change induced by the positive voltage pulse in DA LB films was modified reversibly by applying negative voltage pulse of -20 V.This result is attractive for a rewritable memory system.