荧光材料SrS:Eu,Sm在辐射剂量测量中的应用

采用碳还原法合成了SrS：Eu,Sm,并对光激励发光材料SrS：Eu,Sm的辐射剂量特性进行了研究。将SrS：Eu,Sm材料做成PMMA剂量片在^60Coγ源下接受辐照,然后用自己搭建的在线实时测试系统对剂量片发出的荧光信号进行测量。主要探讨了光激励发光材料SrS：Eu,Sm在辐射剂量测量中的应用。     

Sr_3Ca_2(PO_4)_3X:Eu~(2+)(X=F,Cl,Br)的光激励发光与F色心

研究了Eu~(2+)激活的Sr_3Ca_2(PO_4)_3X晶体中的F色心及光激励发光。讨论了不同卤离子对F色心及其能级结构的影响。探讨了在X光辐照下和光激励发光过程中Eu~(2+)的价态变化及光激励发光过程的机理。     

发光材料BaFBr:Eu的穆斯堡尔谱研究

首次应用穆斯堡尔谱对光激励发光材料BaFBr:Eu进行了研究．穆斯堡尔谱的研究结果印证了光谱学研究得出的结论，即在BaFBr:Eu中, Eu~(2+)，的发光强度远高于Eu~(3+)的发光强度，Eu~(3+)对Eu~(2+)的发光有增强作用．穆斯堡尔谱的研究还为声子对发光中心的影响提供了有用的信息．这些结果对于发光机制的认识是很有帮助的．     

BaFCl：Sm晶体的光激励发光和热释发光

研究了在X射线辐照及光激励发光和热释发光过程中,BaFCl:Sm晶体中钐离子的价态变化和F色心的产生和湮灭过程。提出了如下的BaFCl:sm晶体的光激励发光和热释发光过程:在X射线辐照下,晶体中产生F色心,同时一部分Sm~(3 )俘获空穴形成Sm~(4 ),还有少量的Sm~(3 )得到电子形成Sm~(2 )。在光激励发光和热释发光过程中,从F色心中电离出来的电子与Sm~(4 )复合转变成Sm~(3 )激发态,随后发出Sm~(3 )的特征光辐射。同时在热释发光中,Sm~(2 )还可以与空穴复合,转变成Sm~(3 )的激发态,也发出Sm~(3 )的光辐射。     

锰掺杂对CaS∶Eu光激励发光性能的影响

采用硫化助熔剂法制备了CaS∶Eu, Mn荧光粉.通过测量样品的荧光光谱和紫外光辐照下的光激励发光谱, 发现Mn离子的掺入使CaS:Eu的发光性能明显增强, 存在于基质材料中的陷阱分布因掺入Mn杂质而改变, 形成了新的俘获中心, 引起能量转移. 增大了电子俘获过程中电子和空穴复合的几率, 有利于提高材料的存储性能. 比较了不同浓度下发射光谱的差异, 探讨了掺杂浓度对发光特性的影响. 通过比较光激励发光衰减曲线, 进一步表明了Mn掺杂对CaS∶Eu光激励发光性能的改善.     

锰掺杂对CaS：Eu光激励发光性能的影响

采用硫化助熔剂法制备了CaS：Eu，Mn荧光粉。通过测量样品的荧光光谱和紫外光辐照下的光激励发光谱，发现Mn离子的掺人使CaS：Eu的发光性能明显增强，存在于基质材料中的陷阱分布因掺人Mn杂质而改变，形成了新的俘获中心，引起能量转移。增大了电子俘获过程中电子和空穴复合的几率，有利于提高材料的存储性能。比较了不同浓度下发射光谱的差异，探讨了掺杂浓度对发光特性的影响。通过比较光激励发光衰减曲线，进一步表明了Mn掺杂对CaS：Eu光激励发光性能的改善。     

BaFCI:Tb晶体的热释发光和光激励发光

BaFCl:Tb晶体的光激励发光和热释发光过程为:在X射线辐照下,晶体中产生F色心,同时掺杂的Tb³⁺离子俘获空穴形成Tb⁴⁺离子。X线辐照后的晶体在可见光或热激励下,F色心中释放出的电子与Tb⁴⁺复合成Tb³⁺并处于激发态,随后发出Tb³⁺)子的跃迁辐射。     

BaFCl晶体中的V心及光激励空穴发光

本文首次报道了室温下BaFCl晶体中的V心(空穴色心)及光激励空穴发光。V_1,及V_2,V_3心的吸收峰分别位于205,238和355nm。V_2心与F心在X射线辐照和光激励发光过程中同步形成与衰变,表明V心在X射线影像存储与再现过程中起着与F心同等重要的作用。     

BaF（Cl,Br）：Sm^2＋的光谱烧孔与光激励发光过程

Ｘ射线辐照前后，在ＢａＦ（Ｃｌ，Ｂｒ）：Ｓｍ＾２＋中以５６０ｎｍ的Ｎｄ：ＹＡＧ脉冲光在液氮温度下进行了双光子烧孔实验和光激励发光实验，结果表明，Ｓｍ＾２＋掺杂的碱土金属氟卤化物光谱烧孔过程中伴随着光激励发光过程，这一过程直接影响光谱烧孔过程的进行。     

铈掺杂对BaFBr:Eu2+光激励发光性能的影响

采用一步反应法制备了BaFBr:Eu2+,Ce3+X射线影像存储材料.通过荧光光谱和光激励发光谱研究了材料的光致发光及其经X射线辐照后的光激励发光性质.结果发现,Ce离子的掺入使得BaFBr:Eu2+的发光性能明显增强,存在Ce3+离子向Eu2+离子的能量传递,Ce离子的掺杂浓度为0.7%(摩尔分数)左右时可得到较高的光致发光及光激励发光强度.且掺入Ce3+后,可以有效的形成能稳定存储的较低能级的电子陷阱,使得在信息读出过程中所需激励光能量降低,从而使得读出光的能量与价廉、便携的长波激光器的读出波长匹配得更好.     

Laser-induced luminescence from an excited HgNH3 complex

When a Hg/NH₃ mixture is irradiated at 260 nm or longer wavelengths luminescence appears around 340 nm. The luminescence originates from an excited HgNH³ complex formed through a bound—free transition. Both the luminescence excitation spectrum and the dispersed spectrum have been analysed in terms of postulated potentials for the ground and excited-state HgNH₃ complexes.     

Optical memory and multistep luminescence thermochromism in single crystals of K2Na[Ag(CN)2]3

Single crystals of the layered compound K2Na[Ag(CN)2]3 exhibit a dual emission with high-energy (HE) and low-energy (LE) phosphorescence bands at 313 and 402 nm, respectively. Remarkably, the crystals exhibit "optical memory", in which a new emission band with intermediate energy (IE) at 380 nm is generated upon laser irradiation (lambda ex = 266 nm) at cryogenic temperatures. The irradiated crystals reinstate their original luminescence spectrum upon heating to room temperature and then recooling. In addition to these unusual "write/read/erase" changes, the crystals also exhibit multistep luminescence thermochromism such that the LE/HE intensity ratio increases between 17 and 80 K but then decreases upon further heating. The unprecedented occurrence of both novel phenomena in one compound has been related to reversible photophysical changes instead of irreversible photochemical changes.     

Luminescence emission of natural NaCl

The luminescence properties of synthetic alkali halides in general and different doped synthetic sodium chloride (NaCl) in particular have been widely studied. However, the spectral emission of natural NaCl has been scarcely reported. Accordingly, this work reports on the thermoluminescence (TL), infrared stimulated luminescence (IRSL) and radioluminescence (RL) response of the well-characterized natural NaCl (by means of X-ray fluorescence and differential thermal and thermogravimetric techniques) in the range of 200-800 nm. As observed in the 3D-TL plots, the main emission of the irradiated samples appears in the UV-blue region and can be deconvoluted into four groups of components (at 70, 180, 220 and 315 °C) assuming first order kinetics. The non-irradiated samples exhibited a negligible luminescence signal. The RL response reveals the appearance of five bands peaked at 290, 370, 430, 500 and 620 nm. The IRSL spectral emission shows a low intensity broad band with non-well defined peaks.     

SINGLET OXYGEN QUANTUM YIELD OF SULFUR AND SELENIUM ANALOGS OF PSORALEN

The quantum yield of singlet oxygen production by eight newly synthesized sulfur and selenium analogs of psoralen irradiated with UV-A (366 nm) has been determined in CCl4 with the help of the steady state luminescence technique. The new psoralen derivatives are generally better singlet oxygen producers than psoralen itself. In particular, the replacement of selenophene for furan and/or of thiopyrone for pyrone induces an important enhancement of the singlet oxygen quantum yield.     

BIOLUMINESCENCE OF THE BRITTLE STAR OPHIOPSILA CALIFORNICA

The light-emitting principle of the brittle star Ophiopsila californica has been isolated and purified. It was found to be a green-fluorescent photoprotein (molecular weight 45000) which emits green light (λ_max 500 nm) when H₂O₂ is added, independently of the presence or absence of O₂. The green fluorescence (emission maximum 500 nm, excitation maximum 440 nm) spectrally coincided with the H₂O₂-triggered luminescence, indicating that the green fluorescent chromophore is the light-emitter of the photoprotein luminescence.     

WAVELENGTH DEPENDENCE FOR THE INACTIVATION OF ATP IN THE VACUUM-ULTRAVIOLET REGION ABOVE 140 nm

Radiation effects were investigated on the activity and the structure of adenosine triphosphate in the wavelength range from 140 nm to 260 nm, using monochromatized synchrotron radiation from the INS-SOR storage ring. The sample was irradiated as a thin film in vacuum. The activity of adenosine triphosphate decreased sharply below 180 nm as judged by the luminescence in the luciferin-luciferase assay. From the exponential decay of function, the cross-section for inactivation was calculated to be of the order of 10^-21 m²/photon in the range from 140 to 170 nm. No decrease was detected at wavelengths of 190 nm and above. The calculated quantum yield increased as the wavelength became shorter and reached to 0.20 at 150 nm. The release of adenine at 160 nm-irradiation was detected by thin layer chromatography; no adenosine diphosphate or adenosine monophosphate occurred. Only a trace of adenine was found after 190 nm-irradiation. These results indicate that the broad absorption peak for higher excitations attributable to the base moiety around 190 nm does not cause both structural and functional changes, while the absorption by the sugar-phosphate group produces the rupture of N -glycosidic bond, and probably leads to the loss of function.     

GLASS and PLASTIC PHOTOLUMINESCENCE: INTERACTION WITH AQUEOUS MEDIA and CULTURED MAMMALIAN CELLS

Several types of glass and plastic materials were shown to exhibit intense photoluminescence when irradiated with UV. Water or phosphate buffered saline (PBS) contained within vessels of the respective materials when irradiated, also demonstrated relatively long-lived luminescence. A significant percentage (30%) of cultured mammalian cells were killed when exposed to UV-irradiated glass beads. The nature of the luminescence of water or PBS, or whether this or the photoluminescence of glass is directly responsible for cell toxicity, is unknown. However, we call attention to this phenomenon as a potential complicating factor in photobiological studies.     

LD激发的ZnWO4:Er3+晶体上转换发光

采用Czochralski法生长出ZnWO₄:Er³⁺(Er=0.02mol)单晶,测量了吸收光谱和激发光谱。在波长966nm功率500mW的激光二极管(LD)激发下观察到上转换发光。强度最大的发射峰位于547和558nm,发射光谱分析表明,上转换激发过程与双光子步进吸收有关。     

STUDIES OF THE ROLE OF THE COAT PROTEIN IN THE U.V. PHOTOINACTIVATION OF U(1) AND U(2) STRAINS OF TMV*

Abstract— Two properties of the u.v. inactivation process in the u.v. sensitive U(2) strain have been investigated: (1) The increased binding of protein to RNA induced by irradiation of the virus at 254 nm; (2) The action spectrum for u.v. inactivation of U(2) between 250 nm and 285 nm. The extent of the u.v. induced binding of protein to RNA is similar to that previously found in the resistant U(1) strain, thereby eliminating the possibility that the capacity for this binding phenomenon bears any correlation to the difference in u.v. sensitivities of these two viruses at 254 nm. The results indicate that the radiation induced interaction of protein and RNA in U(1) and U(2) are probably similar. The action spectrum for U(2) resembles the absorption spectrum of the RNA between 250 nm and 285 nm implicating the RNA as the primary absorber leading to inactivation of the virus in this region of the spectrum. Quantum yields calculated for U(2) virus and free TMV-RNA irradiated at 254 nm reveal that the irradiated free RNA may be as much as 1–4 times more sensitive to inactivation at this wavelength than RNA in the intact virus. It is concluded that the coat protein of U(2) probably offers some protection to the enclosed RNA against u.v. damage at 254 nm, therefore, the difference in u.v. sensitivity between U(1) and U(2) TMV at this wavelength is a consequence of a difference in the degree of protection offered by the respective coat proteins to the enclosed RNA.     

THE PHOTOREACTIVITY OF PYRIMIDINE-PURINE SEQUENCES IN SOME DEOXYDINUCLEOSIDE MONOPHOSPHATES AND ALTERNATING DNA COPOLYMERS

Abstract— A reversed-phase HPLC system has been developed which separates the common nucleo-bases from the 6-methylimidazo[4,5- b ]pyridin-5-one (6-MIP) produced on acid hydrolysis of a thymine-adenine photoadduct (TA*) that is formed between adjacent thymine and adenine bases in UV-irradiated polydeoxyribonucleotides. By measuring the relative amounts of adenine and 6-MIP in acid hydrolysates, this system has been used to investigate how polynucleotide conformation affects the yield of TA* in poly(dA-dT) irradiated at 254 nm. The photoreactivity of other pyrimidine-purine sequences has been examined with the deoxydinucleoside monophosphates d(TpI) and d(m⁵CpA) and with the alternating DNA copolymers poly(dA-dU), poly(dI-dC), poly(dG-dC) and poly(dA-dC).poly(dG-dT). Samples were irradiated at 254 nm in aqueous solution and in ice, and at wavelengths >290 nm with acetone as photosensitizer. A photoproduct resembling TA*, and giving 6-MIP on acid hydrolysis, was isolated from d(TpI) irradiated at 254 nm in solution or in ice; d(m⁵CpA) was comparatively unreactive. Acid hydrolysates of the irradiated DNA copolymers were screened by HPLC and by TLC and paper electrophoresis, for the presence of imidazo[4,5- b ]pyridin-5-one, 6-MIP, or other species attributable to specific photoproduct formation. By this criterion, however, none of the copolymers showed evidence of significant photoreactivity in either their single- or double-stranded conformational states. The formation of mixed pyrimidine-purine photoadducts in DNA is therefore probably restricted to T-A doublets.