Measurement of degree of coherence of electron beam emitted from a carbon nanotube tip

1.投射显微镜的研制为研究碳纳米管针尖出射电子束的相干性，研制了电子双棱镜投射显微镜。电子双棱镜可以通过三维调整系统进行精确定位。采用多壁碳纳米管作为电子双棱镜的中心电极。电子纳米棱镜干涉条纹由B.Cho和C.Oshima教授(早稻田大学)发现的电子纳米棱镜干涉条纹与传统电子双棱镜产生的干涉条纹进行了比较。传统电子双棱镜的计算假定从FE针尖发射的电子的波长是恒定的，电子从电子源上的每个点非相干发射。发现前者的干涉条纹与后者的干涉条纹相似。制备单根碳纳米管针尖的两种方法研究了利用钛镍合金和电蚀刻钨针尖表面存在的氧化钨薄膜的方法。研究发现，这两种方法的耐热性都不是很理想。进一步的研究正在进行中。不同五边形发射的电子波对多壁碳纳米管尖端的干涉实验由于微通道板的故障，实验没有进行。碳纳米管尖上五角形发射的电波相干度的测量由于微通道板的故障，测量没有进行。提出了一种新的双曝光电子全息术，它是由两种电子全息图叠加而成的。利用这一技术，直接观测了带电乳胶球周围的电场和铅酸铅铁氧体粒子周围的磁场。这种方法非常简单，对观察电磁微细颗粒非常有用。

1. Construction of projection microscopeProjection microscope equipped with electron biprism was constructed to investigate the coherence of electron beam emitted from a carbon nanotube tip. The electron biprism can be positioned precisely with the 3D-adjusting system. A multiwalled carbon nanotube is used as the central electrode of electron biprism.2. Electron nanobiprism interference fringesElectron nanobiprism interference fringes found by B.Cho and Prof.C.Oshima (Waseda University) were compared with those produced by conventional electron biprism which were calculated assuming that the wavelength of electron emitted from the FE-tip is constant and the electrons are emitted incoherently from each point on the electron source. It was found that the former interference fringes resemble the latter ones.3. Preparation of a single carbon nanotube tipTwo methods using the Ti-Ni alloy and the tungsten oxide thin film existing on the surface of the electrolytically etched tungsten tip were investigated. It was found that the heat-resistance is now not perfect for both methods. The further studies are in progress.4. Interference experiment using the electron waves emitted from different pentagons on a multiwall carbon nanotube tipThe experiment was not performed due to the trouble of the micro channel plate.5. The measurerment of the degree of coherence of electronwave emitted from a pentagon on a carbon nanotube tipThe mesurement was not performed due to the trouble of the micro channel plate.6. Direct visualization of electromagnetic microfiledsA new double-exposure electron holography which is achieved by superposition of two kinds of electron holograms was presented. Using this technique, an electric field around a charged latex sphere and a magnetic field around a bartium ferrite particle have been directly observed. This method is very simple and useful for observing electromagnetic microfileds.