Kunihiko Chiba

H2O trapping on various materials studied by AFM and XPS

Abstract Adsorption and desorption of water on thin films of iron oxide formed on the iron surface were studied by AFM and X-ray photoemission spectroscopy (XPS). The morphological change of iron oxide or water droplets on the surface of iron oxide were observed by AFM. Electronic state of O 1s was observed by XPS after a sample was exposed to distilled water. Several peaks appeared and assignment to oxygen-containing surface species was discussed.

Desorption of tritiated water on materials by photon and electron irradiation

Abstract Desorption behavior of D 2 O or H 2 O, as a simulant of HTO, from the iron surface covered with thin iron oxide, film was studied by electron stimulated desorption (ESD) and photon stimulated desorption (PSD). When the iron was irradiated with electron or photon, water and hydrogen molecules were desorbed. Desorption behavior of water and hydrogen molecules depended on the incident energy of electron or photon. We discussed desorption mechanism of water and hydrogen molecules by electron or photon irradiation. It was found that the electronic excitation process contributes to desorption. Based on these results, tritium decontamination by ESD and PSD was evaluated.

Investigation of Adsorption and Desorption Mechanism of Water on Material Surface

ABSTRACT Desorption behavior of D2O or H2O, as a simulant of HTO, on iron surface covered with thin iron oxide film was studied by photon stimulated desorption (PSD) using deuterium lamp, Hg-Xe lamp and dye laser as photon sources. When the iron was irradiated with photon, water or hydrogen molecules were desorbed. Desorption behavior of water and hydrogen molecules depended on the incident energy of photon. Desorption mechanism of water and hydrogen molecules by photon irradiation is discussed.

Hydrogen Adsorption Behavior on Stainless Steel for Cooling Pipe in Fusion Reactor

Abstract To investigate the hydrogen behavior in/on the Stainless Steel (SS)-304, the deuterium or heavy water was sorbed on the sample by various methods, such as water adsorption, ion irradiation and electrolysis, and the chemical states of iron, chromium, nickel and oxygen were studied by means of X-ray photoelectron spectroscopy (XPS). It was found that the metal oxide and oxyhydroxide, FeOOD or CrOOD, were formed on the surface of SS-304. The oxyhydroxide was dominant on the surface of the sample charged by electrolysis. However, metal oxide was observed on the surface of SS-304 after D2O water adsorption. The thermal desorption spectroscopy (TDS) was also applied to the evaluation of the thermal desoprtion behaviors of D2 and D2O from SS-304. It was found that three peaks were found in the sample charged with electrolysis. Among them, two peaks were also observed in the sample with water adsorption. The first peak, which was only found in the sample charged with electrolysis, suggests the D2 and D2O release by the decomposition of oxyhydroxide, and the second peak was induced by the decomposition of hydroxide or aquo-iron complexes. The third deuterium release would be induced by the desorption of the dissociative absorbed deuterium. It was concluded that the existence and chemical form of oxygen influence the retention of deuterium on/in SS-304.

FT-IR Study on Behavior of Surface Hydroxyls Under Irradiation of Energetic Particles

D2O adsorption and desorption behavior on Fe2O3 have been studied with a Fourier transform infrared absorption spectrometer (FT-IR). The absorption peaks of the O-D stretching vibration band were observed in the region of 2500-2750 cm-1, which were considered to be from the surface OD on the sample. Desorption behavior by irradiation of energetic particles was not uniform but depended on FTIR wave numbers. Hence, desorption of D2O was found to be heterogeneous on the surface.