MECHANISM FOR PHOTOSTIMULATED LUMINESCENCE (PSL) OF BaFX: Eu2^+

Some new photostimulable F centers in the X-rayed BaFX: Eu2^+ were found. Their absorption bands are located in IR region. PSL process of X-rayed BaFX:Eu^(2+) consists of two subordinated process—e^--h^+ recombination and radiative transition of Eu2^+ ions. The latter is a slow and rate-determining step. Dynamics and mechanism of that PSL have been investigated.

Photostimulated Luminescence and Optical Storage in Eu ^(2+)-Doped Fluoride-Oxide Glass Ceramics

Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due to the 5d-4f transition of Eu 2+ was observed. The PSl excitation band peaking at 543 nm is due to the electron trap centers which are located either in the Eu 2+-doped crystallites or in the glass; where exactly they are located in is not yet known. The optical storage properties of this kind of glass ceramic were also studied. By comparing with the investigations on PSL phosphor Eu 2+ doped alkali halides, PSL mechanism in glass ceramics which is still an open question and has to be investigated in further experiments was explained.

Photostimulated Luminescence and F-centers of Sr_3Ca_2(PO_4)_3X:Eu^(2+)(X=F,Cl,Br)

This paper reports the F-centers and photostimulated luminescence of Eu^(2+)-activated Sr_3Ca_2(PO_4)_3X crystals.The influence of various halide ions on the F-centers and their energy level is discussed.The mechanism for the photostimulated luminescence and valence change of Eu ion in that process have been investigated.

PHOTOSTIMULATED LUMINESCENCE ON BaFCl: Eu^(2+) THIN FILM

In this paper, we have succesfully prepared the sample of BaFCl: Eu2+thin film using the vacuum thermal evaporation method and first studied photostimulated luminescence on BaFCl: Eu2+thin film.

Effect of TSL and PSL in Al^(3+)-Doped BaFBr∶Eu^(2+) at Difference Synthesis Conditions

Thermal stimulated luminescence (TSL) and photostimulated luminescence (PSL) were used to investigate the luminescent performance of Al 3+ doped BaFBr∶Eu 2+ in different synthetic conditions. Theory analysis shows that the decay of TSL spectra is different from that of PSL spectra. Theoretical calculation was used to investigate the effects of energy state in Al 3+ doped BaFBr∶Eu 2+ by different synthetic conditions. The relationship of color center’s energy and different synthetic conditions is discussed.

Luminescence property of Eu-doped fluorochlorozirconate glass-ceramics

A series of Eu2＋-doped fluorochlorozirconate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho- toluminescence, photo-stimulated luminescence （PSL） and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290℃ for 10 rain The PSL was attributed to the characteristic emission of Eu2＋ in nano-crystallites of BaCI2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical transparency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.

Luminescence studies of MBrCl:Eu^(2+) (M=Ca,Sr,Ba)

Europium doped MBrCl （M=Ca, Sr, and Ba） phosphors were prepared by solid state reaction in reductive atmosphere. Photolu- minescence （PL）, photostimulated luminescence （PSL） after X-ray irradiation and optical absorption studies of MBrCI：Eu2＋ （M=Ca, Sr, and Ba） revealed that： （1） blue light emission, under the excitation of 300 nm, was observed in all these phosphors; （2） the shape of the emission spectra in CaBrCI：Eu2＋ could be changed by varying the bromine/chlorine ratio during synthesis, while that in SrBrCI：Eu2＋ and BaBrCI：Eu2＋ showed no change; and （3） PSL was observed in SrBrCI：Eu2＋ and BaBrCI：Eu2＋ after X-ray irradiation. Difference absorption spectrum （DAS） in SrBrCl：Eu2＋showed two broad bands centered at about 470 and 570 nm, and DAS in BaBrCl：Eu2＋showed two bands at about 550 and 675 nm, respectively. This enabled the use of He-Ne laser （633 nm） or even semiconductor fight-emitting diodes （LED） instead of gas lasers for photostimulation.

Study of Photostimulable Luminescence Materials Sr_9Ca(PO_4)_6Cl_2:Eu

The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state reaction.The reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PSL),have been systematically inves- tigated.The properties of this PSL phosphor as a material for storing and reproducing the X-ray image in computer-aided radiography have been reported briefly.

PHOTO-AND THERMOSTIMULATED LUMINESCENCE OF BaFCl:Sm CRYSTALS

The valence changes of doped samarium and the creation as well as the annihilation of F-centers in the processes of thermostimulated luminescence (TSL) and photostimulated luminescence (PSL) of BaFCl∶Sm crystal have been studied. As being irradiated by X-ray,a large number of electron-hole pairs are created in the crystal.Most of the electrons may be trapped at the anion vacancies,producing F-centers.The doped samarium ions,which existed mostly in trivalent state (Sm^(3+)),may capture the holes and convert themselves to tetravalent state.So that part of the incident X-ray energy are stored in this nonequilibrium system.On optical and thermal stimulation the stored energy can be liberated as a characteristic emission of trivalent samarium ion.This emission originates from the recombination of the F-center electrons with tetravalent samarium ions,i.e.the F-center electrons may be excited to the conduction band by optical or thermal stirnulation and then recombine with tetravalent samarium ions.This recombination makes the samarium ions to be in situ reduced to the excited state of Sm^(3+),and gives rise to the characteristic emission of Sm^(3+). On the other hand,during X-irradiation a few electrons can be trapped at the sites of trivalent samarium ions and reduce them to divalent state.But the formation of divalent samarium On X-irradiation is very small as compared with that of F-centers and so their influence on the PSL and TSL can be neglected.

柴胡舒肝丸光释光法辐射筛查研究

目的采用光释光法建立柴胡舒肝丸的辐射筛查方法,为柴胡舒肝丸的质量控制和安全用药提供参考。方法结合国家药品评价性抽验工作样品,参照欧盟标准(EN)13751:2009,样品经简单研粉、压饼处理后,利用SURRC PPSL辐照食品筛查系统,直接检测样品的辐射情况。结果所建立方法经方法学考察可行,测定值可反映样品是否经过辐射,阴性对照无干扰。对10家企业102批次样品辐射情况进行检测,其中6家企业生产的26批次样品辐射筛查阳性,存在被辐射杀菌处理的情况,占总抽检批次的25.5%。结论所建立方法无需复杂的样品前处理即可快速定性分析样品辐射情况,操作简便、快速、经济,可为柴胡舒肝丸的质量控制和安全用药提供参考。

含药食同源成分食品辐照检测的光释光方法建立

通过优化光释光(photostimulated luminescence,PSL)辐照食品检测仪的检测参数,建立适用于含药食同源成分的固体饮料及压片糖果的辐照检测方法,应用于市售样品筛查。结果表明:光释光值随脉冲计数、光源辐照度增加呈上升趋势,随脉冲时间增加呈下降趋势。当脉冲计数为30、脉冲时间为0.2 s、光源辐照度为17 mW/cm2时,PSL值最大。在未辐照样品中混入不同比例的经过辐照处理的样品粉末,掺合比例低至1%的样品也能正确识别。盲样试验中,正确率达到100%。稳定性试验结果显示,6个月储存时间对样品定性判定没有影响。筛查的市售36批样品中,有12批样品为阳性。

LiGaSiO_(4):Mn^(2+),Yb^(3+)的热致发光及光激励发光特性研究

目的开发新型多模激励材料LiGaSiO_(4):Mn^(2+),Yb^(3+),分析其光致发光、热致发光及光激励发光特性,为开发多模动态光信息存储及读出提出新思路。方法通过高温固相法制备样品,用光谱仪表征其光致发光性能,用热释光测试其陷阱分布及热致发光性能,用激光器与光谱仪测试光激励发光性能等。结果通过在LiGaSiO_(4)中掺杂Mn^(2+)和Yb^(3+),显示出优异的热致发光及光激励发光特性。结论成功制备出新型绿色长余辉发光材料LiGaSiO_(4):Mn^(2+),Yb^(3+),共掺引入缺陷增强发光性能,实现光信息多模动态读出。

CaS:Eu,Sm的微波合成与发光性能研究

采用微波合成法快速合成了红外光激励发光材料CaS：Eu，Sm。研究了输出功率对样品发光性能的影响，Eu，Sm双掺杂离子的不同掺杂浓度对发光性能的影响（确定了最佳掺杂浓度），不同助熔剂对发光性能的影响。XRD测试结果表明，CaS：Eu，Sm样品为面心立方结构；SEM照片显示样品粒径在400～500nm范围内；光谱分析表明，样品的红外光激励发光响应范围位于800-1600nm，上转换发光峰值位于655nm，对应于Eu^2＋离子4f^65d→4f^7（^8S7/2）跃迁。

电子俘获光存储材料BaLiF_3:Eu^(2+)的光激励发光及光存储性质研究

利用高温固相反应法制备了混晶状的BaLiF3Eu2+样品。其紫外光激发的发射峰与光激励发光峰均在410nm处,属于Eu2+的5d—4f跃迁发光。光激励峰位于660nm,因而可以配用简单廉价的氦氖激光器。根据光谱特征给出了光激励发光的简单机理。测量了该材料光激励发光衰减性能,结果表明BaLiF3Eu2+存储的信息可以方便地擦除掉。该材料具有优良的光激励发光特性,是一类很有发展前途的电子俘获光存储材料。

辐照中药光释光鉴别法的建立与评价

目的在欧盟标准EN 13751方法的基础上,建立可区分辐照中药与未辐照中药的光释光法,并对所建方法进行评价。方法将中药样品的测定结果采用欧盟方法与所建方法进行比较,观察系列剂量辐照后的检出情况和掺合稀释后的检出情况,研究光子计数(PSL)值与F值的重复性,研究经辐照处理样品贮藏后的变化情况,研究盲样检出的正确率,以对所建方法进行科学评价。结果样品所含矿物质的种类和数量影响方法的检出灵敏度,敏感度高者低至0.1 kGy的辐照剂量即可以检出,灵敏度低者1 kGy以上的剂量能够检出。在未辐照样品中混入不同比例的经过辐照处理的药粉,掺合比例低至0.1%的样品也能正确识别。样品10次测定的PSL计数值重复性以及样品3份平行样测得F值的重复性满足要求。盲样测试正确率达100%。可见,所建方法在灵敏度、准确度、稳定性等各方面均能满足鉴别要求。结论所建光释光法鉴别辐照中药具有正确率高、快速简便的特点,与欧盟方法比较,更适合中药产品,判定规则更加简洁明确,而判定结果的准确度与欧盟方法一致,甚至优于欧盟方法。

辐照食品光释光检测法

介绍了辐照食品光释光检测法的工作原理、国内外应用现状、适用范围和优缺点。为方便读者使用该方法,本文结合欧洲标准化委员会EN 13751:2009《食品—用光释光法检测辐照食品》标准与笔者的实际工作经验介绍了光释光检测法的操作步骤。

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。

BaFCl∶Eu^（2＋）中F色心的浓度和光激励截面与温度和紫外线的辐照波长的关系

本文研究了ＢａＦＣｌ∶ＥＵ（２＋）在不同波长的紫外线辐照和不同的测定温度下的光激励发光性质．通过改变激励方式及激励光的扫描方向，给出了ＢａＦＣｌ∶Ｅｕ（２＋）光激励发光过程中，两种Ｆ色心的浓度比值和光激励截面比值与紫外线辐照波长和测定温度的关系．同时我们还研究了在激励读出过程中，对应两种Ｆ色心的光激励发光强度与激励温度的关系，并且给出了相应于Ｆ（Ｃｌ－）心的热激活能．

正电子湮没寿命与BaF_xCl_（2－x）：Eu^（2＋）中缺陷的关系

讨论了光激励发光材料ＢａＦｘＣｌ２－ｘ：Ｅｕ２＋中的缺陷与正电子湮没寿命的关系．通过实验结出随着ｘ值的改变即Ｆ／Ｃｌ比值的变化对形成Ｆ色心的影响，并且给出了ｘ值与Ｆ色心的种类与浓度的关系．

光释光法检测牛黄清心丸(局方)^(60)Co-γ辐照情况

目的采用光释光法建立牛黄清心丸(局方)^(60)Co-γ辐照的检测方法。方法参照欧盟标准(EN)13751:2002,利用SURRC PPSL辐照食品筛查系统,无需前处理,直接检测样品辐照情况。结果测定值可反映样品是否经过辐照,阴性对照无干扰。9个厂家的38批次样品PSL值在28 214~272 412之间,可初步推测所有被测样品均经过^(60)Co-γ辐照灭菌处理。结论所建方法操作简便、快速、经济,可为牛黄清心丸(局方)的质量控制和安全用药提供参考。