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

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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.