Silicone ([SiO(CH3)2]
n
) films were photochemically modified into SiO2 by irradiation with a 157 nm F2 laser. The dissociation of Si–CH3 bonds of silicone simply depended on the photon number of the F2 laser. The quantum yield of the modification was estimated to be approximately 1×10-2. Mechanisms of oxidation and O–H production in the modified films were clarified. The depth of the modification was not limited by the absorption coefficient of silicone because SiO2 of the modified films is transparent for the F2 laser. A fine pattern of the 1.5-µm-thick silicone films could be fabricated by immersing the modified samples in 0.2 wt% hydrogen fluoride solution.
The photochemical surface modification of silicone ([SiO(CH3)2]n) rubber has been successfully demonstrated using a 193 nm ArF excimer laser, and white light of strong intensity was emitted upon exposure to a 325 nm He–Cd laser. The photoluminescence spectra of the modified silicone showed broad peaks centered at 410, 550, and 750 nm wavelengths. The modified surface was carbon-free silicon oxide, and the chemical composition ratio of O/Si was approximately 2. However, the surface was not silica glass (SiO2), as clarified by IR spectroscopy. Instead, nanometer-size particles of silicon oxide were formed on the surface of the modified silicone rubber.
Rustproof, chemical-resistant pure-iron thin films were successfully fabricated by the 157 nm F2-laser-induced surface modification of 50-nm-thick iron thin films. An approximately 2-nm-thick Fe3O4 layer underneath a native Fe2O3 layer of approximately 0.6 nm in thickness was formed on the iron thin films after F2 laser irradiation, as confirmed by X-ray photoelectron spectroscopy. The anodic polarization measurement in a 3 wt % NaCl aqueous solution (quasi-seawater) was conducted; the F2-laser-irradiated samples showed high corrosion resistance to the quasi-seawater. Moreover, no rust was observed on the samples after the immersion test in quasi-seawater for 48 h and longer. The measurement also revealed that the F2-laser-irradiated samples showed high corrosion resistance to a HNO3 aqueous solution. Thus, the micropatterning of iron thin films was demonstrated by the combination of F2 laser irradiation and subsequent HNO3 chemical etching.
The influence of the memory effect on X-ray diffraction, X-ray photoelectron spectroscopy and Raman scattering in the positive electrodes of the nickel metal hydride batteries were investigated. The obtained data of X-ray diffraction, X-ray photoelectron spectroscopy and Raman scattering in the samples shown the memory effect are hardly affected during the charge-discharge processes. The peak intensity of the Raman mode due to the defect of the crystal structure in the samples shown the memory effect is larger than those in the normal and reconditioned samples. These results suggest that the samples shown the memory effect involve more disorder and/or proton vacancy than the normal and reconditioned samples. Consequently, the redox mechanism of the nickel oxide electrode based on the reversible insertion-deinsertion of protons and electrons is deteriorated.
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