为研究材料辐照损伤的产生机制和缺陷的实时演变过程,在GIC4117串列加速器原有的低能负离子注入平台基础上加装光谱测量系统,实现具有"charge-up free"优点的负离子激发发光在线测量。利用20 ke V H-轰击羟基含量为20μg/g,1 ...为研究材料辐照损伤的产生机制和缺陷的实时演变过程,在GIC4117串列加速器原有的低能负离子注入平台基础上加装光谱测量系统,实现具有"charge-up free"优点的负离子激发发光在线测量。利用20 ke V H-轰击羟基含量为20μg/g,1 100μg/g的石英玻璃测量其发射光谱,研究离子束辐照前后样品的吸收光谱。离子轰击过程中,发光中心数目随剂量先增加后缓慢衰减至平衡状态;蓝色和红色波段发光峰发光产额比可能受表面结构的影响稳定在3~4之间,低于Me V H+激发产额比。辐照前后吸收光谱反映的缺陷浓度变化与离子激发石英玻璃光谱强度变化一致。羟基含量较高的石英玻璃,发射光谱强度较低,吸收光谱强度辐照前后相对变化较小,对应产生的弗伦克尔缺陷数目较少。展开更多
The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescen...The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.展开更多
Negative ion-beam-induced luminescence (IBIL) measurements of a pure LiF crystal using 20 keV are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission ba...Negative ion-beam-induced luminescence (IBIL) measurements of a pure LiF crystal using 20 keV are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission bands are observed in the IBIL spectra and the evolvement mechanisms of the corresponding centers are identified. The difference between the IBIL measurements using positive ions and negative ions is that the intensities of luminescence centers can reach the maxima at lower fluences under negative-ion irradiation due to free charge accumulation.展开更多
A new low-energy negative-ion induced luminescence setup was recently developed at the injector of the GIC4117 2 × 1.7 MV Tandem accelerator in Beijing Normal University. In situ luminescence measurements are per...A new low-energy negative-ion induced luminescence setup was recently developed at the injector of the GIC4117 2 × 1.7 MV Tandem accelerator in Beijing Normal University. In situ luminescence measurements are performed on silica glass by using 20key H ions at room temperature. Gauss fitting of the spectra revealed six overlapping components at about 2.7eV, 2.4eV, 1.geV, 1.8eV, 4.2eV, and 3.6eV, which except for the new observed emission band at 3.6eV are assigned to the creation of type lI oxygen-deficient centers, E＇ centers, non-bridging oxygen hole centers with different precursor states, and type-I oxygen-deficient centers. The fitted results of the saturation concentration show that self-trapped exciton recombination at type-lI oxygen-deficient centers is the main luminescence emission process. The evolution of the luminescence intensity and full width at half maximums as a function of ion fluence is also discussed. It is found that the number of recombination centers reaches its maximum at lower Huence, and the area ratio between blue bands and red bands is much lower than that under high energy H＋ ion irradiation.展开更多
文摘为研究材料辐照损伤的产生机制和缺陷的实时演变过程,在GIC4117串列加速器原有的低能负离子注入平台基础上加装光谱测量系统,实现具有"charge-up free"优点的负离子激发发光在线测量。利用20 ke V H-轰击羟基含量为20μg/g,1 100μg/g的石英玻璃测量其发射光谱,研究离子束辐照前后样品的吸收光谱。离子轰击过程中,发光中心数目随剂量先增加后缓慢衰减至平衡状态;蓝色和红色波段发光峰发光产额比可能受表面结构的影响稳定在3~4之间,低于Me V H+激发产额比。辐照前后吸收光谱反映的缺陷浓度变化与离子激发石英玻璃光谱强度变化一致。羟基含量较高的石英玻璃,发射光谱强度较低,吸收光谱强度辐照前后相对变化较小,对应产生的弗伦克尔缺陷数目较少。
文摘The ionoluminescence （IL） spectra of a ZnO single crystal irradiated with 2.5？MeV H＋＋ ions reveal that its intensity decreases with increasing the ion fluence, which indicates that the concentration of luminescence centers decreases with irradiation. The Gaussian decomposition results of the ZnO IL spectrum with a fluence of 1.77×10^11ions/cm^2 show that the spectrum is a superposition of energy levels centered at 1.75eV, 2.10eV, 3.12eV and 3.20eV. The four peaks are associated with electronic transitions from CB to VZnZn, CB to Oii, Znii to VB and the decay of self-trapped excitons, respectively. The results of single-exponential fitting demonstrate that different luminescent centers have different radiation resistance, which may explain why the emission decreases more slowly in the NBE band than in the DBE band. The agglomeration of larger point clusters accounts for the decrease in the concentration of luminescence centers and the increase in the concentration of non-luminescence centers, which indicates that the defect clusters induced by ion implantation act as nonradiative recombination centers and suppress light emission. The results of the photoluminescence spectra of a virgin ZnO single crystal and a ZnO single crystal irradiated with a fluence of 3.4××10^14ions/cm^2 show that compared with the virgin ZnO, the emission intensity of irradiated ZnO decreases by nearly two orders of magnitude, which demonstrates that the irradiation effect reduces radiative recombination and enhances nonradiative recombination. The conclusions of photoluminescence are consistent with the IL results.
文摘Negative ion-beam-induced luminescence (IBIL) measurements of a pure LiF crystal using 20 keV are performed to monitor the formation and annihilation of luminescence centers during ion irradiation. Several emission bands are observed in the IBIL spectra and the evolvement mechanisms of the corresponding centers are identified. The difference between the IBIL measurements using positive ions and negative ions is that the intensities of luminescence centers can reach the maxima at lower fluences under negative-ion irradiation due to free charge accumulation.
文摘A new low-energy negative-ion induced luminescence setup was recently developed at the injector of the GIC4117 2 × 1.7 MV Tandem accelerator in Beijing Normal University. In situ luminescence measurements are performed on silica glass by using 20key H ions at room temperature. Gauss fitting of the spectra revealed six overlapping components at about 2.7eV, 2.4eV, 1.geV, 1.8eV, 4.2eV, and 3.6eV, which except for the new observed emission band at 3.6eV are assigned to the creation of type lI oxygen-deficient centers, E＇ centers, non-bridging oxygen hole centers with different precursor states, and type-I oxygen-deficient centers. The fitted results of the saturation concentration show that self-trapped exciton recombination at type-lI oxygen-deficient centers is the main luminescence emission process. The evolution of the luminescence intensity and full width at half maximums as a function of ion fluence is also discussed. It is found that the number of recombination centers reaches its maximum at lower Huence, and the area ratio between blue bands and red bands is much lower than that under high energy H＋ ion irradiation.
