Study on the mechanism of surface contamination with tritium nder condition and active decontamination

1. 用傅里叶变换红外吸收光谱仪（ET-IR）和四极杆质谱仪研究了D_2O在不锈钢、Cr_2O_3和NiO上的吸附和解吸行为。在2100 ~ 2700 cm^<-1>范围内观察到O-D拉伸振动带，认为这是由物理吸附在样品上的D_2O引起的。表面对D_2O的吸附是不均匀的。O-D振动频率越高，D_2O的解吸速度越慢。光照对D_20脱附有促进作用。250nm的光比400nm和600nm的光更能促进D_2O的解吸。结果表明，O-D波数越高的D_20光激解吸效果越好。用FT-IR研究了Li_2O中氢同位素与缺陷的相互作用。经过热吸收和淬火处理的Li_2O单晶在O-D拉伸振动区出现多峰。这些峰值与温度的关系更大，主要是由于存在缺陷或不存在缺陷的大块Li_2O中O-D的拉伸振动。在控制温度和水蒸气压的条件下，利用原子力显微镜（AEM）成功地观察了石墨和金属氧化物表面水滴的俘获和脱除行为。以HOPG的解理面为理想表面进行了实验。在表面的阶地上观察到少量的液滴。而许多液滴沿着台阶在低于露点的温度。在铁氧化物表面，离子辐照后出现更多的水滴。这意味着表面缺陷成为水捕获的场所。还发现，表面氧化铁的形态随着水的捕获而发生变化。用XPS和UPS观察了氧化铁表面附近氧和铁的电子态。根据Ols的观察。在表面上发现了四种氧气：feexoy中的氧气。含杂质化合物和游离水中的FeOOH。用从头算Hartree-Fock量子化学计算方法研究了氢在Li_2 O（110）表面的解离吸附。通过计算体系总能，计算了H_2解离吸附的吸附热和表面势能。吸附热计算结果表明，H2吸附是吸热吸附。然而，当吸附位点附近存在氧空位时，吸附热变得不那么吸热，并且解离H-H键所需的活化能小于阶地位点。这被认为是由缺陷附近的过量电荷引起的。少

1. D_2O adsorption and desorption behavior on stainless steel, Cr_2O_3 and NiO have been studied with a Fourier transform infrared absorption spectrometer (ET-IR) and a quadrupole mass spectrometer. The O-D stretching vibration band was observed in the region of 2l00-2700 cm^<-1>, which was considered to he from the physically adsorbed D_2O on the sample. Adsorption of D_2O was found to be heterogeneous on the surface. Desorption of D_2O with a higher O-D vibration frequency occurred mote slowly. The light irradiation was found to enhance D_20 desorption. The 250nm light stimulated D_2O desorption more strongly than the one of 400 or 600nm. It seems that D_20 with a higher O-D wave number is more effective for light stimulated desorption.2. The interaction between hydrogen isotopes and defects in Li_2O, using FT-IR.Multiple peaks were observed in the O-D stretching vibration region with Li_2O single crystals which were treated by thermal absorption and quenching. These peaks had differ … More ent dependence on temperature and were attributable to the stretching vibrations of O-D in hulk Li_2O with or without defects.3. We have successfully observed trapping and detrapping behavior of water droplet on the surface of graphite and metal oxides by an atomic force microscope (AEM) with non-contacting mode under controlled temperature and water vapor pressure. The cleavage surface of HOPG was tested as the ideal surface. On the terrace of the surface few droplets were observed. while many droplets along steps at lower temperature than the dew point. On iron oxides, more water droplets appeared when surface was irradiated with ion irradiation. It means surface defects become the sites for water trapping. It was also found that morphology of iron oxide on the surface changes with water trapping.4. Electronic state of oxygen and iron near the surface of iron oxide was observed by XPS and UPS.From the observation of Ols. four kinds of oxygen were found on the surface : oxygen in the FexOy. FeOOH, in compounds with impurities, and in free water.5. Dissociative adsorption of hydrogen on Li_2 O (110) surface has been investigated with ab initio Hartree-Fock quantum chemical calculation technique. Heat of adsorption and surface potential energy for H_2 dissociative adsorption were evaluated by calculating the total energy of the system. The calculated results on adsorption heat indicated that H2 adsorption is endothermic. However, when an oxygen vacancy exists adjacent to the adsorption site, the heat of adsorption became less endothermic and the activation energy required to dissociate the H-H bonding was smaller than that for the terrace site. This is considered to be caused by the excess charge localized near the defect. Less