1Faculty of Engineering, Tokyo Institute of Technology, Tokyo. Present address: Mechanical Engineering Laboratory, 1-2, Sakura-Mura Namiki, Niihari-Gun, Ibaraki
A new experimental technique and set-up for measuring the optically stimulated exo-electron emission (OSEE) is developed. In order to obtain the test surface of uniform quality and to realize the stable OSEE measurement, orthogonal cutting was conducted in a vacuum chamber and a monochromatic light was focused on the finished metal surface during the cutting. By changing the location of the focused light, it is possible to measure OSEE at arbitrary time after the surface creation.
The adsorption process of gas molecules to the surface can be studied by comparing the electron energy distribution with the emission intensity distribution which are obtained for various atmospheres with changing the wave length of stimulating light. It is found that adsorption of water and methanol molecules (of which dipolemoment 6.17×10-30 C⋅m and 5.64×10-30 C⋅m respectively) enhances OSEE and reduces the work function about 0.5 eV, while the adsorption of carbon-tetrachloride and benzene (of which dipolemoment are zero) does not show any effect.
According to the emission characteristics obtained, it appears that the machined surface may consist of portions of different work function and the well known change of contact potential with time elapsed after the surface creation may be attributed to the change of area ratio of the portions.
On adsorbed copper surface an emission center which is similar to what observed in oxides and alkali halides was found.
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