【作者】 刘平；

【导师】 李劲；

【作者基本信息】 复旦大学 ， 物理电子学， 2005， 博士

【摘要】 本文采用双课题形式，以第一部分为主体内容。 ●第一部分： 金属有机络合物由于其独特的光电性质，近年来引起了人们的广泛关注。其中，M（Cu、Ag）-TCNQ络合物是一种重要的模型材料；由于它们具有电双稳特性与光致变色特性，因而成为高密度信息存储方面的重要候选材料。这类材料的高质量薄膜通常是由金属、有机物分层真空蒸发并通过固体扩散反应而获得。因而，了解其中的传质动力学规律与机制及其稳定性，对薄膜制备、使用具有重要的实际意义。此外，传质特性是材料的基本性质之一。以前，传质特性研究主要集中于无机固体，而对有机物中的传质特性研究很少，特别是化学位梯度下有机物中的传质研究尚不存在系统研究工作，因此，这种研究对于了解有机物中的特殊传质性质具有较为普遍的科学意义。 本文选择了金属Ag和有机材料TCNQ作为研究对象，研究了Ag／TCNQ双层膜体系的动力学规律，包括：由Ag和TCNQ双层膜形成金属有机络合物过程中的传质机制和传质参数，以及络合物的热稳定性问题。 主要研究结果如下： （1） 采用双源交替真空蒸发的方法，在玻璃基板上制备了摩尔比为1:1的Ag／TCNQ双层膜，并利用透射光谱作定标，即根据光谱曲线形状与时间以及络合产物数量间的关系，实现了薄膜的传质研究的表征技术。 （2） 建立异质元素标志法，利用SIMS测量了金属与有机物反应前后相关元素的不同分布，得知Ag／TCNQ中的传质过程是Ag⁺在已经形成的Ag-TCNQ络合物中迁移的结果，Ag⁺迁移中存在换位现象。 （3） 通过对相同温度不同厚度以及同一厚度不同温度条件下Ag／TCNQ双层膜的络合反应的研究（温度范围为60～110℃），得到了传质动力学规律和传质参数。结果表明，传质距离与传质时间符合抛物线规律；传质常数k′的对数与绝对温度T满足线性关系，对应的Arrhenius方程为： k′=k′₀exp（-Q／（RT））=5.62×10^-6exp（-（0.53eV）／（kT））cm²／s； Ag／TCNQ双层膜形成Ag-TCNQ络合物的微观机制是Ag⁺在Ag-TCNQ络合物中的间隙置换。 （4） 研究了不同厚度的TCNQ薄膜和Ag-TCNQ金属有机络合物薄膜在不同温度下的热稳定性，计算了TCNQ和Ag-TCNQ的热激活能，两者分别为0.74eV和0.81eV。 ●第二部分： 随着科技的发展，医用回旋加速器小型化加快，为PET（正电子发射断层显像）、PET／CT的全面发展提供了支持。近10年来，国内PET中心（指同时具备回旋加速器、热室和PET或PET／CT扫描仪）的增加速度惊人，目前已经达到30多个，而PET和PET／CT扫描仪的数量更是达到60多台，回旋加速器数量也达到30多台。由于PET中心在运行过程中，需要处理大量的放射性问题，因此，很有必要对PET中心运行中涉及的放射性进行系统、全面的监测、分析和讨论，并提出合理的建议，以加强辐射防护措施，保证人员的安全。现在虽然有少数资料对辐射问题进行了研究，但是，都不全面，缺乏系统性。本部分详细监测了PET中心的辐射剂量，分析了影响辐射剂量的因素，测量并计算了工作人员受到的辐射剂量，为讨论了辐射的防护措施等，为保证人员安全提供参考和指导。 主要研究结果如下： （1）回旋加速器在生产¹¹C、¹³N、¹⁵O、¹⁸F时，大厅内除了一个点外，其余各处的γ射线和中子辐射剂量率均小于15μSv／h，大厅外的周围环境辐射剂量率都小于0.5μSv／h。 （2）回旋加速器大厅内的辐射剂量率正比与束流强度，即束流越大，辐射剂量率也越大。 （3）热室周围的γ辐射剂量率小于0.39μSv／h。 （4）工作人员的年辐射剂量最大不超过5.22mSv，小于国家辐射安全标准中关于职业人员的年辐射剂量限值（职业人员年限值为每年20mSv）。 （5）工作人员的年辐射剂量与受检者数量有关：受检者数量越多，工作人员的年辐射剂量也越多。导师说明： 该论文作者为我校华山医院PET中心回旋加速器主管工程师，按预定的培养计划，其在职博士论文的两部分分别在材料科学系与华山医院进行。研究工作以第一部分为主，主要内容为金属有机双层膜传质的基础问题研究；第二部分工作为辅助内容，主要涉及核辐射监测内容。材料科学系与华山医院PET中心总体合作的背景是：利用PET中心的同位素制备和材料系的传质研究特长，在同位素示踪传质研究、放射性元素示踪传质研究（包括核辐射监测）中进行交叉合作。该论文工作属于该计划中的一个交叉研究预备部分。更多还原

【Abstract】 Part 1:Great attention was paid in metalorganic complexes in recent years due to then-special optical and electric properties, in which M （Ag, Cu）-TCNQ complexes are one kind of model materials of great importance. M-TCNQ is one of the candidate materials for high-desity information storage because of their bistable and photochromic properties. The thin films of this type of materials with high quality are usually prepared by solid diffusive reaction between the metal and organic after successive vacuum evaporation. As one of the important properties, transport study was focused on inorganic materials while little on organic amterials, especially when there exist chemical potential gradient. Therefore, it is of great scientific importance to understand the special properties in the organic.In this part, Ag and TCNQ were selected as the evaporation materials and the transport behavior in Ag/TCNQ thin films was studied, including the transport mechanism during the formation process of Ag-TCNQ complex from Ag/TCNQ bilayer thin films, the calculation of activation energy, and the thermal stability of Ag-TCNQ complex.The results are as follows:（1） Ag/TCNQ bi-layer thin films with good molar ratio between Ag and TCNQ are prepared on glass by successive vacuum evaporation of Ag and TCNQ with the measurement of the optical transmittance spectra of Ag/TCNQ thin films.（2） The tracer method was established because of the similar properties of Ag and Cu when they react with TCNQ. The diffusion behavior in Ag/TCNQ is studied using Cu as a tracer, in combination with profile analyses by secondary ion mass spectroscopy （SIMS）. The results show that the diffusion mechanism in Ag-TCNQ thin film is Ag ion diffusion accompanied by ion exchange.（3） The transport behavior of Ag-TCNQ was studied at different temperature （60～110℃） with different thickness. The results showed that the transport distance （x） and transport time （t） accord with parabola law （x² = 2k’t） at 90℃. And the transport coefficient k’ andthe temperature T accord with Arrhenius Law, which could be expressed And the transport mechanism was discussed, which was believed to be interstitialcy mechanism.（4） The thermal stability of TCNQ films and Ag-TCNQ complex thin films with different thickness were studied at different temperatures. The activation energy of evaporation for both TCNQ and Ag-TCNQ was calculated, which were 0.74eV and 0.81eV, respectively.Part 2:The development of science and technology pushes the process of cyclotron miniaturization, which supply the development of PET （Positron Emission Tomography） and PET/CT with pharmaceutical support. In recent years, the quantities of PET centers in China increased dramastically, and more than 30 PET centers were established, in which cyclotrons, hotcell and PET （or PET/CT） scanners were included. Up to now, the number of PET and PET/CT scanners is more than 60, while the number of cyclotrons is more than 30.As there is much radiation in PET centers, it is necessary to monitor and analyze the radiation systematically and in detail, and put forward reasonable suggestions to strengthen the radiation protection to make all the staff safe. Although there are a few literatures about the radation dose and radiation protection, radiation data are not fully and systematically included.In this part, the radiation dose and dose rate were monitored and evaluated, including the points inside/outside of the cyclotron room and around the hotcell. The factors affecting the radiation dose rate aroud the cyclotron were analyzed, and the annual radiation doses of staff were calculated. After that, the methods of radiation protection were discussed.The results are as fellows:（1） During the production of ¹¹、 ¹³N、 ¹⁵O and ¹⁸F with target current of 40μA, the radiation dose rate of most of the measuring points in the cyclotron room was less than 15μSv/h except one point, and the radiation dose rate of all the measuring points outside the cyclotron room was less than 0.5μSv/h.（2） The linear relationship between the radiation dose rate and the target current showed that the higher beam current, the higher radiation dose rate.（3） The Gamma radiation dose rate around the hotcell is less than 0.39μSv/h.（4） The annual radiation doses of occupational people were no more than 5.22mSv, which is less than the safety standard of our country （20mSv for occupational people）.（5） The annual radiation dose of occupational people is related to the examinees. The more examinees, the higher radiation dose.更多还原