Development of STM combined with synchrotron-radiation light source and its application to elemental analysis and spin observation

STM结合同步辐射光源的研制及其在元素分析和自旋观测中的应用

• 批准号: 14350016
• 负责人: HASEGAWA Yukio
• 金额: $ 9.66万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14350016/
• 关键词: scanning tunneling microscope; core level excitation; synchrotron radiation; elemental analysis

We have developed an ultrahigh vacuum (UHV) STM system with which we can take atomically resolved STM images under an Iiradiation of synchrotron radiation light source. In order to do that, we designed an anti-vibration system including a vibration-isolation table which can be fitted in a narrow space of beamline. Since sites of beamlines in synchrotron-radiation light source are usually quite noisy electrically and mechanically, which is completely inappropriate for STM, we needed to consider carefully to avoid the noises to disturb the operation of STM, and successfully took atomically resolved STM images of the Si(111)7x7 surface under the irradiation.We also succeeded in taking adsorption spectra of the sample element by using the probe tip as a detector; it was found that the photoinduced current increases when the irradiated light energy is above 101eV, an adsorption edge of Si 2p, demonstrating a possibility that the STM tip can detect photoelectron emitted from core states of sample. Compared with the previous work done with a X-ray tube, the photoinduced current by the synchrotron is larger by a factor of more than 100. High intensity of the light and tunability of a light energy to that of a high adsorption crosssection are the main reasons for the high detection.After an modificatIon of the measurement system, we could also measure the photoinduced current quantitatively. From the quantitative measurement we characterized a spatial resolution of this elemental detection method by using a sample with a mixture of Au-induced 5x2 and Si7x7 surfaces and a Si substrate on which 2-micron size aluminum dots are regularly arranged. We also developed a method to focus the detection area on the tip for improving the spatial resolution by coating the tip with an insulating polymer and found successfully working.

我们研制了一套超高真空STM系统，在同步辐射光源的照射下，可以获得原子级分辨的STM图像。为此，我们设计了一种抗振系统，包括一个隔振台，它可以安装在一个狭窄的空间光束线。由于同步辐射光源中光束线的位置通常具有很强的电噪声和机械噪声，这对于STM来说是完全不合适的，因此需要仔细考虑以避免噪声干扰STM的运行，并成功地拍摄了Si（111）的原子分辨STM图像，7 × 7表面进行了辐照，并成功地用探针针尖作探测器拍摄了样品元素的吸收光谱;发现当辐照光能量超过Si 2 p的吸附边101 eV时，光生电流增加，说明STM针尖可以探测到样品芯态发射的光电子。与以前用X射线管所做的工作相比，同步加速器的光生电流大100倍以上。高光强和光能量对高吸收截面的可调谐性是高探测率的主要原因，通过对测量系统的改进，我们还可以定量地测量光生电流。从定量测量中，我们通过使用具有Au诱导的5x 2和Si 7 x7表面的混合物的样品和在其上规则地排列2微米尺寸的铝点的Si衬底来表征该元素检测方法的空间分辨率。我们还开发了一种方法，通过用绝缘聚合物涂覆尖端来将检测区域聚焦在尖端上以提高空间分辨率，并成功地工作。

项目成果

T.Matsushima et al.: "Development and trial measurement of synchrotron-radiation-light-illuminated scanning-tunneling-microscope"Review of Scientific Instruments. (in press). 75 (2004)

T.Matsushima 等：“同步辐射光照明扫描隧道显微镜的开发和试验测量”科学仪器评论。

T.Matsushima et al.: "Development and trial measurement of synchrotron-radiation-light- illuminated scanning-tunneling-microscope"Review of Scientific Instruments. 75,6月号(印刷中). (2004)

T. Matsushima 等人：“同步辐射光照明扫描隧道显微镜的开发和试验测量”科学仪器评论 75，6 月号（2004 年出版）。

T.Matsushima: "Development and trial measurement of synchrotron-radiation- light-illuminated scanning-tunneling-microscope"Review of Scientific Instruments. 75,5月号(掲載予定). (2004)

T.Matsushima：“同步辐射光照明扫描隧道显微镜的开发和试验测量”科学仪器评论 75，5 月号（待出版）。