Development of an apparatus for the analysis of chemical reactions on surfaces equipped with a Helium beam apparatus.

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The purpose of this project is to develop an apparatus with which surface reactions and surface structures can be observed, by applying the techniques of supersonic molecular beam. With the apparatus, we want to control the surface reaction by varying the translational energy of molecules impinging on the surface, and observe the property of the reaction using the Helium beam scattering technique.The apparatus is composed of a molecular beam apparatus, a manipulator with which the position of the sample is controlled, a rotatable mass spectrometer, a vacuum chamber and a pumping system.The molecular beam apparatus is working well in point of the triply differential pumping and the control of the translational energy of molecules. As to the manipulator, by the use of stepping motors for use in UHV,the sample can be controlled with high precision which is needed for the experiment of He beam scattering. The rotatable mass spectrometer and a double differential pumping system constructed to reduce the background gas are rotated around the sample.By performing the experiments described below, we ascertained the enough performance of the apparatus.1.We performed He diffraction experiment. We observed the diffraction pattern corresponding to LiF (100) surface structure in the angular distribution of He atoms scattered from the surface when He beam is directed to the sample. We confirmed that the surface structure is measured by the use of He beam.2.We observed that the intensity of specular reflection of He beam from Ni (100) surface decrease with increasing the amount of the adsorbate.3.We observed spectra of submonolayr CO and NH_3 adsorbed on Ni (100) surface.