辐射变色薄膜的质子辐照响应

 用J-2.5质子静电加速器提供的质子束,对研制的一种高灵敏度新型辐射变色膜进行质子辐射响应研究。该变色膜以聚乙烯醇缩聚物为基质,以类丁二炔化合物为有机染色材料,质子能量为2.0 MeV,辐照注量为1.0×10¹⁰～1.0×10¹² cm^-2。用光谱响应测试薄膜的辐射效应显示：变色薄膜颜色由粉红渐变为蓝色, 并随着辐照剂量的增加而逐渐加深;用图像分析仪分析辐照后靶材的光密度发现,图像的光密度随聚焦斑距离的增大而减小;用分光光度计测试其吸收光谱发现,主吸收峰值出现在660 nm附近,且吸收峰处的响应吸光度与质子注量具有较好的线性关系;对新型变色薄膜辐照后持续效应的研究表明,变色膜辐照后续效应微弱,辐照后可以立即测量,且对测量环境变化不敏感。     

一种新型辐射变色膜的γ射线辐照研究

报道了以高聚物为载体,以有机染料及添加剂为变色指示剂体系,制备一种辐射变色膜。这种辐射变色膜为无色透明固体薄膜,经60Co γ射线辐照后,其颜色变为蓝色。辐照后样品的紫外-可见吸收光谱表明,在可见光区其最强吸收峰出现在624 nm附近。在10～90 kGy的剂量范围内,不含添加剂的辐射变色膜的光密度变化与吸收剂量呈线性关系,而含有添加剂的辐射变色膜对γ射线辐照的响应在50 kGy时就达到饱和。同时还探索了该体系辐照效应的化学反应机理。     

溶剂对辐射变色膜吸收剂量的影响

本实验室分别选用无水乙醇和丙酮溶液为溶剂制成两种类型的辐射变色膜, 并对这两种辐射变色膜进行了60Co γ射线与紫外线辐照, 研究不同溶剂对辐射变色膜吸收剂量的影响。实验发现, 60Co γ射线与紫外线辐照后, 使用丙酮作溶剂的辐射变色膜变色效果比无水乙醇的更加明显。在相同的辐照剂量下, 使用丙酮作为溶剂的变色膜比用无水乙醇的光谱吸收峰(680 nm)值平均高65.5%。γ射线辐照时, 用丙酮作为溶剂的辐射变色膜变色的辐照剂量下限为0.5 Gy, 而用无水乙醇做为溶剂的为1 Gy; 紫外辐照时, 用丙酮为溶剂的辐射变色膜吸收峰处吸收剂量的线性响应区间为0～6×100 μJ/cm2, 而用无水乙醇做为溶剂的为0～36×100 μJ/cm2。     

高感度辐射变色薄膜电子剂量计

 以聚乙烯醇缩聚物为基质,以类丁二炔化合物为有机染色材料,研制了一种高灵敏度新型辐射变色膜。采用JJ-2型范格拉夫静电加速器对变色薄膜进行剂量范围为15～90 Gy的电子束辐照,结果显示:变色薄膜颜色由粉红渐变为蓝色,并随着辐照剂量的增加而逐渐加深;分光光度计测试其吸收光谱,发现主吸收峰值出现在675 nm附近,且吸收峰处的响应吸光度与电子注量具有较好的线性关系;对变色层厚度为20～80 μm的变色膜,吸收峰处的响应吸光度与其变色层厚度也成线性关系;添加不同比例的协同剂,能提高变色薄膜的响应灵敏度;变色膜辐照后续效应微弱,辐照后可以立即测量,且对测量环境变化不敏感。     

新型辐射变色凝胶的紫外辐照研究

将类丁二炔化合物自组装成纳米囊泡后,均匀分散于凝胶载体中,研制出一种新型的辐射变色凝胶剂量计。用电镜观测了囊泡形貌,采用CL-1000型紫外交联仪对凝胶进行辐照,测试并研究了凝胶对紫外辐照的变色响应、辐射后效应、扩散效应等剂量学性能。结果表明:该辐射变色凝胶在5~150mJ/cm2能量密度范围内对紫外线辐照具有良好的响应线性,同时克服了扩散效应、辐射后效应、成型能力差等现有凝胶剂量计的不足。该辐射变色凝胶剂量计适于光学扫描方式测量剂量分布。     

1.06 μm连续激光辐照TiO2/SiO2/K9薄膜元件温升规律研究

利用1．06μm连续激光在不同强度下辐照TiO2／SiO2／K9薄膜元件,实验中用红外热像仪测量激光辐照在TiO2／SiO2／K9元件表面引起的温升随时间的变化,通过数据处理,获得激光辐照区域最高温度随辐照时间的增加而增加。同时,给出材料温升随材料发射率的变化关系。并用程序模拟不同激光强度下薄膜温度场的分布,通过实验测量数据校正数值模拟计算结果,给出TiO2／SiO2／K9薄膜元件温度随激光辐照强度和辐照时间的变化规律。并且获得在薄膜厚度方向：薄膜表面温度最高,基底与薄膜接触处温度最低;沿径向：激光辐照中心温度最高,边沿温度最低。     

1.06μm连续激光辐照TiO_2/SiO_2/K_9薄膜元件温升规律研究

利用1.06μm连续激光在不同强度下辐照TiO2/SiO2/K9薄膜元件,实验中用红外热像仪测量激光辐照在TiO2/SiO2/K9元件表面引起的温升随时间的变化,通过数据处理,获得激光辐照区域最高温度随辐照时间的增加而增加。同时,给出材料温升随材料发射率的变化关系。并用程序模拟不同激光强度下薄膜温度场的分布,通过实验测量数据校正数值模拟计算结果,给出TiO2/SiO2/K9薄膜元件温度随激光辐照强度和辐照时间的变化规律。并且获得在薄膜厚度方向:薄膜表面温度最高,基底与薄膜接触处温度最低;沿径向:激光辐照中心温度最高,边沿温度最低。     

紫外辐照对聚醚酰亚胺薄膜介电性能的影响北大核心CSCD

研究了不同紫外辐照时间对聚醚酰亚胺(PEI)薄膜介电性能的影响。采用FT-IR和SEM表征了PEI薄膜的分子结构和微观形貌。结果表明,紫外辐照后PEI薄膜在1742cm^(-1)处的吸收峰比原薄膜增大,说明PEI分子链中的C=O基团随辐照时间的增加而增加,并在薄膜表面产生了微裂纹。对PEI薄膜的介电性能进行的研究结果表明,随着紫外辐照时间的增加,PEI薄膜的介电常数和介电损耗增大,而表面电阻率下降,体积电阻率基本不变。并随紫外辐照时间的增加,直流击穿强度呈先增加后降低的趋势,一定辐照剂量可使薄膜发生交联反应,使击穿场强较原薄膜提高20%以上。     

低温退火对HgCdTe中波光导器件γ辐照效应的影响

 研究了低温退火对HgCdTe中波光导探测器γ射线辐照效应的影响。经过剂量为1 Mrad的辐照后，器件的性能下降。对经过辐照的器件进行低温退火，退火温度范围为313～333 K，退火时间在5~16 h之间不等。在相同条件下测量了器件辐照前后及不同退火温度、不同退火时间下的体电阻、响应率、探测率和响应光谱。通过对比辐照前后及不同退火温度下性能参数的变化，分析了退火对器件的γ辐照效应的影响。实验表明：低温退火对辐照引起的性能的下降有一定的恢复作用。     

质子辐照对MQ硅树脂增强的加成型硅橡胶质损及热性能的影响

 采用空间综合辐照模拟设备研究了100 keV和150 keV能量的质子辐照对MQ硅树脂增强的加成型硅橡胶的损伤及其对硅橡胶热性能的影响。试验结果表明：质子辐照后，硅橡胶表面出现损伤裂纹，随辐照能量和剂量的增加，裂纹的数量增多，裂纹增大；质子辐照后，硅橡胶的质量有所损失，其质损率随辐照能量和剂量的增加而增加；质子辐照后硅橡胶的耐热性随辐照剂量的增加先略有增加而后下降，经辐照后的硅橡胶在玻璃态和玻璃转变区的温度区间内收缩率降低，而在高弹态的温度区间内膨胀率增加。     

第一性原理计算N掺杂对InNbO_4电子结构的影响

宽带隙(3.83 e V)半导体光催化材料InNbO_4在紫外光作用下具有分解水和降解有机物的性能.最近实验发现了N掺杂InNbO_4具有可见光下分解水制氢的活性.为了从理论上解释这一实验现象,本文采用基于密度泛函理论的第一性原理计算了N掺杂对InNbO_4的能带结构、态密度和光学性质的影响.分析能带结构可得,N掺杂后在InNbO_4的价带(O 2p)上方形成N 2p局域能级,导致电子跃迁所需的能量减小.吸收光谱表明,N掺杂后InNbO_4的光吸收边出现了红移,实现了可见光吸收.     

第一性原理计算N掺杂对InNbO4电子结构的影响

宽带隙（3.83 eV）半导体光催化材料InNbO4在紫外光作用下具有分解水和降解有机物的性能。最近实验发现了N掺杂InNbO4具有可见光下分解水制氢的活性。为了从理论上解释这一实验现象，本文采用基于密度泛函理论的第一性原理计算了N掺杂对InNbO4的能带结构、态密度和光学性质的影响。分析能带结构可得，N掺杂后在InNbO4的价带（O 2p）上方形成N 2p局域能级，导致电子跃迁所需的能量减小。吸收光谱表明，N掺杂后InNbO4的光吸收边出现了红移，实现了可见光吸收。     

Improved performance of silicon‐nanoparticle film‐coated dye‐sensitized solar cells

Silicon (Si) nanoparticles with average size of 13 nm and orange–red luminescence under UV absorption were synthesized using electrochemical etching of silicon wafers. A film of Si nanoparticles with thickness of 0.75 µm to 2.6 µm was coated on the glass (TiO₂ side) of a dye‐sensitized solar cell (DSSC). The cell exhibited nearly 9% enhancement in power conversion efficiency (η) at film thickness of ～2.4 µm under solar irradiation of 100 mW/cm² (AM 1.5) with improved fill factor and short‐circuit current density. This study revealed for the first time that the Si‐nanoparticle film converting UV into visible light and helping in homogeneous irradiation, can be utilized for improving the efficiency of the DSSCs. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrophilicity of amorphous TiO2 ultra-thin films

The UV-light-induced hydrophilicity of amorphous titanium dioxide thin films obtained by radio frequency magnetron sputtering deposition was studied in relation with film thickness. The effect of UV light irradiation on the film hydrophilicity was fast, strong and did not depend on substrate or thickness for films thicker than a threshold value of about 12 nm, while for thinner films it was weak and dependent on substrate or thickness. The weak effect of UV light irradiation observed for the ultra-thin films (with thickness less than 12 nm) is explained based on results of measurements of surface topography, UV-light absorption and photocurrent decay in vacuum. Comparing to thicker films, the ultra-thin films have a smoother surface, which diminish their real surface area and density of defects, absorb partially the incident UV light radiation, and exhibit a longer decay time of the photocurrent in vacuum, which proves a spatial charge separation. All these effects may contribute to a low UV light irradiation effect on the ultra-thin film hydrophilicity.     

As2S8玻璃条形波导的光激励法制备技术研究

为了在As2S8薄膜中制备条形波导,实验研究了As2S8薄膜光致折射率变化和密度变化的现象,采用棱镜耦合、X线衍射和远红外反射光谱等测试技术,确认了As2S8薄膜经紫外光辐照后薄膜密度增高、折射率增大的现象。采用可见光吸收谱测试技术,确认了经紫外光辐照的As2S8薄膜不发生黑化现象。在归纳了实验规律的基础上,提出并采用紫外光激励的方法试制了As2S8条形波导,采用自动调芯端面耦合的方法激励As2S8条形波导的导模,结果显示该波导具有良好的导波特性。     

Photocatalytic degradation of ciprofloxacin drug in water using ZnO nanoparticles

We report the synthesis of nanostructure ZnO semiconductor with ～2.1 nm diameter using a chemical precipitation method. The resulting nanoparticles were characterized by X-ray diffraction analysis (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The optical properties were investigated by UV–vis and fluorescence techniques. The absorption spectra exhibit a sharp absorption edge at ～334 nm corresponding to band gap of ～3.7 eV. The fluorescence spectra displayed a near-band-edge ultraviolet excitonic emission at ～410 nm and a green emission peak at ～525 nm, due to a transition of a photo-generated electron from the conduction band to a deeply trapped hole. The photocatalytic activity of the prepared ZnO nanoparticles has been investigated for the degradation of ciprofloxacin drug under UV light irradiation in aqueous solutions of different pH values. The results showed that the photocatalytic degradation process is effective at pH 7 and 10, but it is rather slow at pH 4. Higher degradation efficiency (～50%) of the drug was observed at pH 10 after 60 min. Photodegradation of the drug follows a pseudo-first-order kinetics.     

Electron mobility in poly(3-hexylthiophene) enhanced by gamma-ray irradiation

Gamma-ray irradiation effects on the photoresponsive thin-film devices based on the regioregular poly(3-hexylthiophene) (RR-P3HT) conjugated polymer have been studied by means of atomic force microscopy, UV–vis absorption, photoluminescence (PL), and time-of-flight measurements. As a result, increased light absorption in the red region and PL quenching induced by the irradiation were observed. Besides, enhancement of the electron/hole mobilities, attributable to improved ordering or increased nanodomain size of the P3HT thin films, was revealed.     

Photophysical characteristics of polyaniline with photochromic azobenzene side groups

Photochromic characteristics and optical molecular reorientation in conducting polymer such as polyaniline derivatives containing photochromic azobenzene moieties (PAPNPAPOA) in side chain are studied. Changes in the UV—vis absorption, refractive index, thickness, contact angle and morphology of these films after irradiation of a linearly polarized light with a wavelength of 365nm are measured. The trans-cis isomerization of PAPNPAPOA is proved irreversible even after withdrawing the UV light for a long time. That the structure of main-chain attends by the trans-cis isomerization of side-chain is confirmed by the absorption and the solution colour during the UV irradiation. These effects are discussed by taking the trans-cis isomerization of azobenzene into consideration.     

Photoresponsive conductance switching of multi-walled carbon nanotubes bearing covalently linked spironaphthoxazine

Multi-walled carbon nanotubes functionalized with a photochromic spironaphthoxazines (MWCNTs-SPO) were synthesized by the reaction between the hydroxyl group of SPO and the carbonyl chloride groups on the surface of MWCNTs. The functional spirooxazine photochromic groups on the surface of MWCNTs were identified by the X-ray photoelectron spectroscopy. As a novel derivative of MWCNTs, photoresponsive conductance switching of the MWCNTs-SPO was demonstrated under a 365 nm UV light irradiation. A simple photoinduced resistance measurement following the cyclic irradiation of UV light shows a very reversible response. The effect of the electron injection in the SPO is rationalized in terms of the HOMO–LUMO energy levels of both spiro and merocyanine forms.     

Plasmon enhanced light absorption in bulk heterojunction organic solar cells

Silver nanospheres (Ag NSs) buffer layers were introduced via a solution casting process to enhance the light absorption in poly (3‐hexylthiophene) (P3HT) and [6,6]‐phenyl‐C61 butyric acid methyl ester (PCBM) bulk heterojunction organic solar cells. These Ag NSs, as surface plasmons, could increase the optical electric field in the photoactive layer whilst simultaneously improving the light scattering. As a result, this buffer layer improves the light absorption of P3HT:PCBM blend and consequently improves the external quantum efficiency (EQE) of organic solar cells. In this work, different sizes of Ag NSs plasmon‐enhanced layer were investigated, with the aim of optimizing the performance of devices. UV‐vis spectrometer measurement demonstrates that the total optical absorption of P3HT:PCBM blend films in the spectral range of 350–650 nm is increased by ～4 and 6% with incorporation of the 20 and 40 nm Ag NSs, respectively. The J_sc was shown to increase by ～21 and 24% for 20 and 40 nm Ag NSs, respectively. This is due to the extra photogenerated excitons by the plasmonic resonance of Ag NSs. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)