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和四极质谱计研究了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)&g~(-1)范围内观察到O-D伸缩振动带，认为这是样品上物理吸附的D_2O所致。D2O在表面上的吸附是非均相的。O-D振动频率较高的D_2O脱附较慢。光照对D20的解吸有促进作用。250 nm光对D_2O脱附的刺激作用比400 nm和600 nm强。结果表明，D_20具有较高的O-D波数，对光刺激脱附更为有效。用FT-IR研究了氢同位素与Li_2O中缺陷的相互作用。经热吸收和淬火处理的Li_2O单晶在O-D伸缩振动区观察到多个峰。这些峰具有不同的…对温度的依赖性更强，这主要归因于有无缺陷的Li_2O壳体中O-D的伸缩振动。利用原子力显微镜(AEM)，在控制温度和水蒸气压力的条件下，用非接触模式成功地观察到了水滴在石墨和金属氧化物表面的捕获和脱陷行为。确定HOPG的解理面为理想解理面。在表面的台地上观察到很少的液滴。而在低于露点的温度下，许多液滴沿着台阶前进。在氧化铁表面，离子辐照后，表面出现较多的水滴。这意味着表面缺陷成为了水的捕捉点。研究还发现，随着水的滞留，表面氧化铁的形貌也发生了变化。用XPS和UPS观察了氧化铁表面附近氧和铁的电子态。在表面发现了四种氧：FexOy中的氧。FeOOH，在有杂质的化合物中，在自由水中。用从头算Hartree-Fock量子化学计算方法研究了氢在Li_2O(110)表面的解离吸附。通过计算体系的总能量，计算了该体系的吸附热和氢解离吸附的表面势能。吸附热的计算结果表明，氢气的吸附是吸热的。然而，当吸附中心附近存在氧空位时，吸附热变得不那么吸热，解离H-H键所需的活化能小于平台中心。这被认为是由缺陷附近的过量电荷引起的。较少

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