流动注射-氢化物发生-原子荧光光谱仪数学模型优化研究

流动注射-氢化物发生-原子荧光光谱法由于具有灵敏度高、测量范围宽、分析速度快等很多优点,在卫生、环保、地质、冶金等行业得到了广泛应用。但是,影响氢化物发生-原子荧光光谱仪灵敏度和谱峰展宽的因素很多,一般都是通过多次实验寻找最佳实验条件,实验条件的优化比较困难。针对这一问题,根据氢化物发生化学反应的特点以及检测系统的组成原理,利用质量守恒等物理定律,提出了一个测试系统的数学模型,建立了各实验参数与仪器灵敏度和谱峰展宽系数之间的函数关系,以对-氨基苯胂酸标准品的测试为例,通过理论仿真与实验结果相比较,证明这个模型能很好的模拟实验系统。最后,利用提出的数学模型,本文给出了各参数与灵敏度和谱峰展宽的关系图,提出气液分离器的容积、载流流速和进样体积是影响系统灵敏度和谱峰展宽的主要因素,利用这个关系图,综合调整三个参数,可以使灵敏度提高到原来的2.9倍,谱峰展宽缩小到原来的0.76,为优化实验条件提供了理论指导。     

2-[(4-氯苯基亚氨基)甲基]-8-羟基喹啉质子转移的理论研究

研究了2-[(4-氯苯基亚氨基)甲基]-8-羟基喹啉的三种质子转移途径: 分子内质子转移、水分子辅助质子转移和甲醇分子辅助质子转移. 以该席夫碱化合物的晶体结构作为模型, 在B3LYP/6-31＋G(d)水平上, 优化得到稳定态和过渡态的几何构型. 对三类质子转移前后的结构、能量、红外光谱、化学位移进行研究, 结果表明水分子辅助质子转移和甲醇分子辅助质子转移中, 水和甲醇分子利用氢键作用参与质子转移过程, 形成七元环状过渡态, 大大降低了反应的能垒, 有利于质子的转移, 氢键在降低活化能方面起着重要作用.     

OH~- absorption and nonvolatile holographic storage properties in Mg:Ru:Fe:LiNbO_3 crystal as a function of Mg concentration

Mg:Ru:Fe:LiNbO3 crystals with various concentrations of MgO (in mole) and fixed content of RuO2 and Fe2O3 (in mass) are grown with the Czochralski method from the congruent melt. Their infrared transmission spectra are measured and discussed to investigate the defect structure. With the increase of Mg2+ concentration the blue nonvolatile holographic storage capability is enhanced. The nonvolatile holographic storage properties of dual-wavelength recording of Mg(7 mol%):Ru:Fe:LiNbO3 nonvolatile diffraction efficiency, response time, and nonvolatile sensitivity reach 59.8%, 70 s, and 1.04 cm/J, respectively. Comparing Mg(7 mol%):Ru:Fe:LiNbO3 with Ru:Fe:LiNbO3 crystal, the response time is shortened apparently. The nonvolatile diffraction efficiency and sensitivity are raised largely. The mechanism in blue photorefractive nonvolatile holographic storage is discussed.     

Influences of Mg^2＋ ion on dopant occupancy and upconversion luminescence of Ho^3＋ ion in LiNbO3 crystal

The effects of a Mg^2＋ ion on the dopant occupancy and upconversion luminescence of a Ho^3＋ ion in LiNbO3 crystal are reported. The birefringence gradient of the crystal is measured to investigate the optical homogeneity. The X-ray powder diffraction spectrum and the upconversion luminescence are used to investigate defect structure and spectroscopic properties of Mg,Ho：LiNbO3. Under 808-nm excitation, blue, red, and very intense yellow-green bands are observed. Based on the energy levels of Ho^3＋ in LiNbO3, and the pump intensity dependence of the observed emission, an excitation scheme is presented. The upconversion emission spectra reveal an enhancement of upconversion intensity when the Mg^2＋ ions are introduced into Ho：LiNbO3. The main upconversion mechanism is discussed in this work.     

Mg2+对Ce∶Fe∶LiNbO3晶体光折变性能的作用和影响

在Ce(0.1wt%)∶Fe(0.08wt%)∶LN中掺进摩尔分数为(0.2%,0.4%,0.6%)的MgO,采用提拉法生长Mg∶Ce∶Fe∶LN晶体.测试晶体的吸收光谱,Mg∶Ce∶Fe∶LN晶体的吸收边相对Ce∶Fe∶LiNbO3晶体发生紫移,Mg(6%)∶Ce∶Fe∶LN晶体OH-吸收峰移到3 532 cm-1,研究OH吸收峰移动机理.以二波耦合光路测试Mg∶Ce∶Fe∶LN晶体的指数增益系数和响应时间,发现Mg∶Ce∶Fe∶LN晶片厚度减小时指数增益系数显著增加.首次采用光爬行效应解释指数增益系数增加机理.     

Optical properties of Mg~(2+),Yb~(3+),and Ho~(3+) tri-doped LiNbO_3 crystals

A series of LiNbO_3 crystals tri-doped with Mg~(2+),Yb~(3+),and Ho~(3+) are grown by the conventional Czochraski technique.The concentrations of Mg~(2+),Yb~(3+),and Ho~(3+) ions in Mg:Yb:Ho:LiNbO_3 crystals are measured by using an inductively coupled plasma atomic emission spectrometry.The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal.The light-induced scattering of Mg:Yb:Ho:LiNbO_3 crystal is quantitatively described via the threshold effect of incident exposure energy flux.The exposure energy(E_r) is calculated to discuss the optical damage resistance ability.The exposure energy of Mg(7 mol):Yb:Ho:LiNbO3 crystal is 709.17 J/cm~2,approximately 425 times higher than that of the Mg(l mol):Yb:Ho:LiNbO_3 crystal in magnitude.The blue,red,and very intense green bands of Mg:Yb:Ho:LiNbO_3 crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties.The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process.The up-conversion emission mechanism is discussed in detail.This study indicates that Mg:Yb:Ho:LiNbO_3 crystal can be applied to the fabrication of new multifunctional photoluminescence devices.