Development of nano-scale surface elemental analysis using pulse excitation by evanescent light and evaluation of material functions

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The analysis of the chemical composition, the chemical structure and the chemical state of the local superfine site of the surface of materials is very important for the elucidation of the emergence mechanism of their functions and their properties. It also leads to excellentmethods for controlling their functions and the development of new materials with higher functions.In this work, the authors attempted to develop a new technique using the concept of ultraviolet photoelectron spectroscopy (UPS) and the evanescent light for excitation, which is induced from a capillary probe of scanning nearfield optical microscope. Since the spot size obtained by the evanescent light does not depend on the wavelength but on the aperture of the probe, the evanescent light froma capillary with ultrafine aperture can excite an extremely small local site of the material surface. After a home-made UPS apparatus was constructed, various fundamental discussions were carried out about instrumental and experimental parameters ; the optimal way for preparation of the capillary probe was established and the dispersion property of an energy analyzer with a cylindrical mirror adopted in our apparatus and the amplification property of a channeltron multiplier chosen as the detector were investigated minutely. An electron-oscillation type helium lamp was adopted as the light source since it emits stablyunder low helium pressure and it can be easily connected to a high-vacuumsystem. The discharge characteristics of the helium lamp such as the relationship between the gas pressure and the emission strength were confirmed. UPS spectra on the surface of the palladium-deposited silicon crystal were measured as an application of our method and the change in the surface of the substrate was analyzed in relation to the thermal treatment.