Eu(p-PBA)_3phen1/2H_2O的高分辨光谱和Raman光谱Eu(p-PBA)3phen1/2H2O的高分辨光谱和Raman光谱*张颖唐波金林培(北京师范大学化学系,北京100875)吕少哲黄世华(中国科学院激发

配合物Ｅｕ（ｐ－ＰＢＡ）３ｐｈｅｎ１／２Ｈ２Ｏ（ｐ－ＰＢＡ：对苯基苯甲酸酸根离子；ｐｈｅｎ：邻菲咯啉）在紫外光激发下，能发出很强的红色荧光．以Ｅｕ（Ⅲ）离子为光谱探针，７７Ｋ下测得其高分辨激发和发射光谱，选择激发配合物的５Ｄ０能级，得到两组不同的发光光谱，表明配合物中Ｅｕ（Ⅲ）离子有两种不同的化学环境．配合物的喇曼光谱中，羧基阴离子的反对称伸缩振动和对称伸缩振动谱带是明显分裂和带肩峰的宽带，说明配合物中羧基同时存在多种配位方式     

Free-form lens design for wide-angle imaging with an equidistance projection scheme

An algorithm of free-form lens design is presented that can realize wide-angle imaging in conjunction with conventional imaging devices. The wide-angle image obtained through the free-form lens and the camera is not affected by distortions. The formula for the free-form lens surfaces is derived. The surface profile of the free-form lens can be generated through solving a differential equation expressing the camera-viewing angle as a function of the angle of incidence on the free-form lens surface. The surfaces preserve a linear relationship between the angle of incidence of light onto the surface and the angle of refraction into the imaging device.     

Optical properties of ErFOD-doped polymers and fabrication of channel waveguides

ErFOD-doped P(MMA-co-GMA) (poly-methyl-methacrylate-co-glycidyl-methacrylate) polymer film was synthesized. The NIR photoluminescence (PL) spectrum of the material showed strong characteristic emission of Er³⁺ ions with broad full width at half-maximum (FWHM) of 55 nm. The rib channel waveguide using ErFOD-doped P(MMA-co-GMA) was designed and fabricated. The loss and gain measurements of the waveguides were also characterized. Further theoretical analysis on Er³⁺ ions in P(MMA-co-GMA) was performed using Judd-Ofelt theory. The results showed that it is a promising material for the elaboration of laser or optical amplifier.     

Analytical Dielectric Spectrum Formula Based on Representative Frequencies

基于电介质复折射率的实验数据,采用最小二乘法结合选取的代表频率拟合得到了电介质的介电谱解析表达式,可以得到电介质在全频段的光频常数和介电常数. 研究了三个典型液态电介质,水、乙醇和甲苯的介电谱. 在实验数据可以获取的频率范围内,采用解析表达式得到的光频常数与采用Kramers-Kronig转换得到的折射率实部和实验得到的折射率虚部吻合得很好. 基于介电谱解析表达式可以预测目前实验无法测量的区域的介电谱.     

C2H2 Overtones Near 12300 cm-1 Revisited with a Very Sensitive Cavity Ring-down Spectrometer

利用单模连续的钛宝石激光器, 构建了一台光腔衰荡光谱仪, 其可探测的最小吸收可达1.8×10^-10/cm. 该光谱仪被用来记录C₂H₂分子在12240～12350 cm^-1的泛频光谱. 与在同一波段测量的已报到的CRDS和激光腔内吸收光谱仪结果比较,本测量同时具有更好的灵敏度和精度. 由此,获得了乙炔分子在12290.12、12311.82和12350.61 cm^-1附近高泛频谱带更准确的振转参数     

动态超高压微射流对糯米淀粉结构的影响

以6%的糯米淀粉溶液为原料,并采用扫描电子显微镜(SEM),紫外-可见(UV/Vis),偏光显微(PLM),X射线衍射(XRD)分析动态超高压微射流处理对糯米淀粉微观结构的影响。结果表明：动态超高压微射流处理后,扫描电镜显示不同压力处理下的糯米淀粉颗粒结构受到不同程度的破坏,经过160 MPa处理后,淀粉颗粒被冲击成片状; 紫外-可见分析中碘兰值变小,支链淀粉含量减小,表明超高压处理过程中支链淀粉的结构被破坏; 偏光显微显示糯米淀粉颗粒的偏光十字随着处理压力的增加逐渐模糊,经160 MPa处理后,多数淀粉颗粒偏光十字消失; X射线衍射分析表明在120 MPa处理后,相对结晶度开始降低,但降低幅度较小。     

卫星搭载紫花苜蓿种子的拉曼光谱分析

为了了解卫星搭载对紫花苜蓿种子化学特性的影响,揭示空间诱变机理,文章利用傅里叶变换拉曼光谱法对卫星搭载当代的紫花苜蓿种子进行了研究。结果表明,与地面对照相比,飞行组在358和553 cm-1处的峰强增加,814,1 122,1 531,1 743 cm-1处的峰强降低,通过谱带归属发现,增强的358和553 cm-1分别与DNA和Ca2+有关,降低的4个峰与糖类、脂类有关。这说明经过卫星搭载后,苜蓿种子的DNA和Ca2+的量出现增加趋势,糖类与脂类的量出现降低趋势。其可能原因是(1)种子主动修复诱变产生的DNA损伤时,消耗部分贮存能量所致;(2)空间飞行过程中的超重导致种子细胞内的Ca2+ 浓度升高;(3)飞行因子导致种子提前萌发,DNA大量合成与复制,种子储藏的能量提前降解消耗。这一结果将对苜蓿空间诱变机理研究有重要参考价值。     

Glassy metallic plastics

This paper reports a class of bulk metallic glass including Ce-, LaCe-, CaLi-, Yb-, and Sr-based metallic glasses, which are regarded as glassy metallic plastics because they combine some unique properties of both plastics and metallic alloys. These glassy metallic plastics have very low glass transition temperature (Tg~25oC to 150oC) and low Young’s modulus (~20 GPa to 35 GPa). Similar to glassy plastics, these metallic plastics show excellent plastic-like deformability on macro-, micro- and even nano-scale in their supercooled liquid range and can be processed, such as elongated, compressed, bent, and imprinted at low temperatures, in hot water for instance. Under ambient conditions, they display such metallic properties as high thermal and electric conductivities and excellent mechanical properties and other unique properties. The metallic plastics have potential applications and are also a model system for studying issues in glass physics.     

Birthrates and delay times of Type Ia supernovae

Type Ia supernovae (SNe Ia) play an important role in diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology. However, the nature of the progenitors of SNe Ia is still unclear. In this paper, according to a detailed binary population synthesis study, we obtained SN Ia birthrates and delay times from different progenitor models, and compared them with observations. We find that the Galactic SN Ia birthrate from the double-degenerate (DD) model is close to those infe...