The electronic structures of BaMgF4 crystals containing an F colour centre are studied within the framework of the fully relativistic self-consistent Direc-Slater theory, using a numerically discrete variational （DV...The electronic structures of BaMgF4 crystals containing an F colour centre are studied within the framework of the fully relativistic self-consistent Direc-Slater theory, using a numerically discrete variational （DV-Xa） method. It is concluded from the calculated results that the energy levels of the F colour centre are located in the forbidden band. The optical transition energy from the ground state to the excited state for the F colour centre is about 5.12 eV, which corresponds to the 242-nm absorption band. These calculated results can explain the origin of the absorption bands.展开更多
Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%）...Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%） single crystals （hereafter called crystal-I）. The TL glow exhibited four glow peaks in the temperature region 300-500 K. The TL response with dose was studied up to -7.5 kGy. The total glow showed linear, supra linear and exponential growth with dose. The TLE showed bands characteristic of Dy^3＋ ions （around 1.65, 1.87, 2.18 and 2.63 eV） and sodium associated （SA） colour centres （CCs） such as MNa （around 1.67 eV） and XNa （a new SA CC, with an emission band around 2.63 eV）. The OA bands of MNa CC around 3.23 and 2.07 eV were found to decrease with temperature almost in accordance with the TL glow. The R＋A centre absorption around 2.48 eV was found to grow with temperature initially and then decayed. The formation/growth of the CCs R＋A and XNa might be from the conversion of the irradiation produced CC MNa. An attempt was made to explain the TL mechanism in the present system.展开更多
The variation of the optical absorption (OA) and photoluminescence (PL) spectra with temperature was studied on γ-irradiated CaF2:Dy:Pb:Na single crystals. The OA spectrum showed bands around 2.05, 3.20, 3.82 and 6.2...The variation of the optical absorption (OA) and photoluminescence (PL) spectra with temperature was studied on γ-irradiated CaF2:Dy:Pb:Na single crystals. The OA spectrum showed bands around 2.05, 3.20, 3.82 and 6.20 eV which could be attributed to different sodium associated (SA) colour centres (CCs) such as MNa and RA+ . Heating the crystal indicated the annihilation and formation of different SACCs. The excitation spectrum for the characteristic Dy3+ emission at 2.14 eV immediately after irradiation was...展开更多
基金supported by the Foundation of Shanghai Municipal Education Committee,China (Grant No. 09YZ210)the Shanghai Leading Academic Discipline Project (Grant No. S30502)
文摘The electronic structures of BaMgF4 crystals containing an F colour centre are studied within the framework of the fully relativistic self-consistent Direc-Slater theory, using a numerically discrete variational （DV-Xa） method. It is concluded from the calculated results that the energy levels of the F colour centre are located in the forbidden band. The optical transition energy from the ground state to the excited state for the F colour centre is about 5.12 eV, which corresponds to the 242-nm absorption band. These calculated results can explain the origin of the absorption bands.
基金supported by the encouragementsupport rendered by the Management of SSN
文摘Therrnoluminescence （TL） glow, thermoluminescence emission （TLE） and thermal decay （TD） of optical absorption （OA） bands were studied on γ-irradiated CaF2：Dy （0.010at.%）：Pb （0.188at.%）：Na （0.026at.%） single crystals （hereafter called crystal-I）. The TL glow exhibited four glow peaks in the temperature region 300-500 K. The TL response with dose was studied up to -7.5 kGy. The total glow showed linear, supra linear and exponential growth with dose. The TLE showed bands characteristic of Dy^3＋ ions （around 1.65, 1.87, 2.18 and 2.63 eV） and sodium associated （SA） colour centres （CCs） such as MNa （around 1.67 eV） and XNa （a new SA CC, with an emission band around 2.63 eV）. The OA bands of MNa CC around 3.23 and 2.07 eV were found to decrease with temperature almost in accordance with the TL glow. The R＋A centre absorption around 2.48 eV was found to grow with temperature initially and then decayed. The formation/growth of the CCs R＋A and XNa might be from the conversion of the irradiation produced CC MNa. An attempt was made to explain the TL mechanism in the present system.
文摘The variation of the optical absorption (OA) and photoluminescence (PL) spectra with temperature was studied on γ-irradiated CaF2:Dy:Pb:Na single crystals. The OA spectrum showed bands around 2.05, 3.20, 3.82 and 6.20 eV which could be attributed to different sodium associated (SA) colour centres (CCs) such as MNa and RA+ . Heating the crystal indicated the annihilation and formation of different SACCs. The excitation spectrum for the characteristic Dy3+ emission at 2.14 eV immediately after irradiation was...
