In order to study the mechanism of irradiation-induced damage ofbotanic samples caused by low energy heavy ions, transmission energy spectrum mea-surement was performed. Kidney bean slice samples 100μm in thickness w...In order to study the mechanism of irradiation-induced damage ofbotanic samples caused by low energy heavy ions, transmission energy spectrum mea-surement was performed. Kidney bean slice samples 100μm in thickness were irradi-ated by 50 kev N+ ions. The irradiation beam current density was about 30μA/cm2,and the irradiation ion doses were 1×1015, 1×1016, 3×1016 and 1×1017 ions@cm-2,respectively. A target set up that could greatly reduce the incident ion current densitywas designed to achieve the damage-free measurement. The 3.2 MeV H+ transmittedion energy spectrum measurement was carried out before and after the irradiation.From the transmission ion energy spectrum, it was found that the kidney bean sliceitself was structurally inhomogeneous compared with the PET films (C10HsO4). Ourresults indicated that the average mass thickness changed little when the N+ iondose was below 3×1016 ions.cm-2, but changed obviously whcn ion dose was beyond3×1016 ions.cm-2.展开更多
Development of a reactive nanocement is a new approach to improve the physical and chemical properties of construction materials. However, due to the decreased size of cement particles, beam damage during transmission...Development of a reactive nanocement is a new approach to improve the physical and chemical properties of construction materials. However, due to the decreased size of cement particles, beam damage during transmission electron microscope （TEM） observation becomes more severe than in conventional cement. In this work, irradiation damage to nano-C2S （dicalcium silicate） is observed and studied by in-situ evolution of diffraction patterns （DP）, high resolution TEM （HRTEM）, and electron energy-loss spectroscopy （EELS）. The results show that the damage to nano-C2S occurs through a decomposition reaction. Nano-C2S is first amorphized, and then re-crystallized into CaO nano-crystals with average size of 7 nm surrounded by an amorphous matrix of Si and SiO2. During this process, C2S particles exhibit volume shrinkage. The damage energy causing the reaction was analyzed and electron-electron inelastic scattering produced radiolysis and heat, leading to the observed phenomena.展开更多
基金Supported by the National Natural Science Foundation of China (No.19675004 and No.19890300)
文摘In order to study the mechanism of irradiation-induced damage ofbotanic samples caused by low energy heavy ions, transmission energy spectrum mea-surement was performed. Kidney bean slice samples 100μm in thickness were irradi-ated by 50 kev N+ ions. The irradiation beam current density was about 30μA/cm2,and the irradiation ion doses were 1×1015, 1×1016, 3×1016 and 1×1017 ions@cm-2,respectively. A target set up that could greatly reduce the incident ion current densitywas designed to achieve the damage-free measurement. The 3.2 MeV H+ transmittedion energy spectrum measurement was carried out before and after the irradiation.From the transmission ion energy spectrum, it was found that the kidney bean sliceitself was structurally inhomogeneous compared with the PET films (C10HsO4). Ourresults indicated that the average mass thickness changed little when the N+ iondose was below 3×1016 ions.cm-2, but changed obviously whcn ion dose was beyond3×1016 ions.cm-2.
文摘Development of a reactive nanocement is a new approach to improve the physical and chemical properties of construction materials. However, due to the decreased size of cement particles, beam damage during transmission electron microscope （TEM） observation becomes more severe than in conventional cement. In this work, irradiation damage to nano-C2S （dicalcium silicate） is observed and studied by in-situ evolution of diffraction patterns （DP）, high resolution TEM （HRTEM）, and electron energy-loss spectroscopy （EELS）. The results show that the damage to nano-C2S occurs through a decomposition reaction. Nano-C2S is first amorphized, and then re-crystallized into CaO nano-crystals with average size of 7 nm surrounded by an amorphous matrix of Si and SiO2. During this process, C2S particles exhibit volume shrinkage. The damage energy causing the reaction was analyzed and electron-electron inelastic scattering produced radiolysis and heat, leading to the observed phenomena.
