低能质子辐照ZnO/silicone白漆产生微观损伤的红外光谱研究

Study on damage effects of low energy protons on ZnO/silicone white paint using infrared spectrum

通过空间综合辐照模拟设备对能量小于200 keV质子辐照下ZnO/silicone白漆光学性能变化及损伤机理进行研究。结果表明,ZnO/silicone白漆的光学性能退化主要发生在可见光区,太阳吸收比随质子辐照能量、注量的增加而增大。借助傅里叶变换红外光谱分析技术研究了质子辐照ZnO/silicone白漆时有机硅树脂的光学性能退化机理。质子辐照使ZnO/silicone白漆中游离氧含量增加,氧化硅原子上的有机取代基使Si—C链断裂,并生成活性羟基,而这种活性羟基能促使有机硅树脂内Si—O—Si键的裂解。同时Si—O—Si链内氧原子未成键的孤对电子与邻近硅原子的3d空轨道配位,降低了π*轨道的能量,提高了对光吸收的几率,增强了n→π*电子跃迁,使吸收带红移,从而导致ZnO/silicone白漆光学性能退化。

The change in optical properties and the damage mechanism of ZnO/silicone white paint caused by low energy protons were investigated in terms of ground-based simulation testing. The results show that the solar absorptance ratio increases with the increase of irradiation fluence of proton as well as the proton energy. Under proton exposure, the degradation in optical properties of ZnO/silicone white paint mainly occurs in the visible radiation region of the solar spectrum. The damage mechanism was studied by Fourier transform infrared spectrum. The amount of free oxygen increases under proton exposure. Free oxygen would oxidate the radicals in the silicone binder and form active hydroxide radical （-OH）, which could accelerate the break of Si-O-Si bond. Meanwhile, the no-bonding lone-pair electron of oxygen atom in Si-O-Si bond forms coordinate with 3d empty orbit of neighboring silicon atom. Therefore, the energy of π° orbit decreases, the probability of optical absorption increases, the n→π° electronic transition enhances, and the absorption band broadens and shows red-shift. The above phenomenon will result in the degradation of optical properties of ZnO/silicone white paint under proton exposure.