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molecular beams on Ni(111) surface dependending on kinetic energy井上 敬介*; 寺岡 有殿
Protection of Materials and Structures from the Space Environment; Astrophysics and Space Science Proceedings, Vol.32, p.521 - 530, 2013/00
In this study, the oxidation states of Ni(111) surface, made by irradiation of a supersonic O molecular beam (SSOMB), were analyzed using synchrotron radiation photoemission spectroscopy (SR-XPS). The surface temperature was 300 K during measurement. After irradiation of SSOMB on the Ni surface to some extent, the evolution of the surface oxides were observed by core level photoemission spectra of Ni
P and O1
so that oxygen uptake curves were measured at every translational energy of O beam. The initial sticking rate increased as translational energy increased from 0.06 eV to 1.0 eV, slightly decreased up to 2.2 eV, and a remarkable re-increase was observed in the region around 2.3 eV. These results imply that high speed O molecules adsorb via two potential barriers.
横田 久美子*; 田川 雅人*; 松本 康司*; 古山 雄一*; 北村 晃*; 神田 一浩*; 戸出 真由美; 吉越 章隆; 寺岡 有殿
Protection of Materials and Structures from the Space Environment; Astrophysics and Space Science Proceedings, Vol.32, p.531 - 539, 2012/08
Stability of hydrogen in Diamond-like carbon (DLC) film under simulated space environment, i.e., hyperthermal atomic oxygen, vacuum ultraviolet (VUV) and soft X-ray exposures has been studied. Hydrogen in DLC was released by low-energy atomic oxygen beam exposure, whereas the gasification reaction of carbon atom needed collision energy above 3 eV. The desorption process in the deep region required a higher collision energy. The density of hydrogen decreased 11% by atomic oxygen exposure, and was independent of the collision energy. Photon exposure also releases hydrogen from DLC. High-energy photons in soft X-ray promote the hydrogen desorption even from deeper region with high efficiency. It was considered that soft X-ray could release bonded hydrogen which is not released by VUV or atomic oxygen exposures.
田川 雅人*; 岸田 和博*; 横田 久美子*; 松本 康司*; 吉越 章隆; 寺岡 有殿; Zhang, J.*; Minton, T. K.*
Protection of Materials and Structures from the Space Environment; Astrophysics and Space Science Proceedings, Vol.32, p.547 - 555, 2012/08
Volatile products were measured from two types of diamond-like carbon films under the hyperthermal atomic oxygen (AO) beam bombardment. It was clearly observed that CO and CO were formed at the conventional hydrogenated DLC surface by hyperthermal AO beam exposure. Desorption rates of CO and CO are constant with AO fluence which reflects the constant erosion rate of the hydrogenated DLC. In contrast, Si-doped DLC shows decrease in amount of CO and CO with increasing AO fluence. Oxidation of Si atoms at the DLC surface was detected by X-ray photoelectron spectroscopy. This is the evidence that SiO film formed at the DLC surface could prevent AO reaction with C atoms in DLC which leads to loss of DLC. Since a self-healing capability can be expected on Si-doped DLC, metal doping is a promising technology for space application of DLC.
