Nonlinearity in Intensity versus Concentration Dependence for the Deep UV Resonance Raman Spectra of Toluene and Heptane

Abstract: The relation between Raman scattering, resonance Raman scattering, and absorption is reviewed to determine to what extent quantitative analysis can be applied in resonance Raman spectroscopy. In addition, it is demonstrated experimentally that normal Raman spectra can be dramatically inhibited by absorption and resonance Raman effects. Raman spectra of toluene and heptane mixtures—with progressively increasing concentrations of heptane—were measured using 229-nm laser excitation. The results show that the characteristic band intensities are not directly proportional to the relative concentrations of the compounds and deviate due to absorption resonance effects. An approximated mathematical model is developed to demonstrate that the intensities of the normal Raman scattering bands are suppressed. An inhibition coefficient K_i is introduced to describe the situation and determine the penetration depth. Most remarkably, it is shown that the intensity of the resonance Raman scattering bands can be constant even when the concentration ratios differ substantially in the sampled mixtures.     

日食对Ne发射光谱强度的影响

为了观测日食时刻日－地空间发生的异常物理现象，本工作采用了观测Ne放电管光源的Ne光谱变化的方法，观测结果表明，日食对Ne光谱的强度产生影响，越接近食甚时刻，Ne光谱强度越弱。     

PbWO4晶体发光强度的温度依赖

对X射线激发下的PbWO4晶体发光强度的温度依赖关系(110-300K)进行了研究,对其I-T曲线中的结构结合热释光进行讨论,利用陷阱解释了I-T曲线中'反常'结构存在的原因.     

Features of the Temperature Dependence of Graphene Oxide Resistivity

The Raman spectra and the temperature dependence of the resistivity of graphene oxide grown upon continuous heating and cooling on a glass substrate is studied in air in the temperature interval of 300–550 K. It is established that the intensity of the D-peak falls relative to the G-peak, the maximum of which shifts toward lower frequencies in Raman spectra. Partial removal of oxygen-containing functional groups is accompanied by a reduction in resistivity from 5.6 × 10⁹ to 5.4 × 10⁹ Ω. In the temperature intervals of 300–350 K and 300–375 K, the resistivity is constant upon graphene oxide heating and cooling, respectively.     

YLiF4: Er3+, Tm3+, Yb3+中Tm3+浓度对上转换发光的影响

利用水热法合成了YLiF4: Er3 , Tm3 , Yb3 , 其中Er3 和Yb3 的浓度保持固定不变, 分别为1 mol%和1.5 mol%, Tm3 浓度变化范围是2 mol%～8 mol%. 在这种共掺杂体系中, 同时观察到了Er3 , Tm3 和Yb3 的吸收, 且Tm3 的吸收随着其浓度的增强而增强. 在980 nm光的激发下, 当Tm3 浓度很小时, 这种材料的上转换发光为白光. 其中蓝光主要来源于Tm3 的激发态1G4到基态3H6的跃迁, 绿光来源于Er3 的4S3/2和2H11/2到基态4I15/2的跃迁, 红光既来源于Tm3 的1G4→3F4的跃迁, 也来源于Er3 的4F9/2→4I15/2的跃迁. 并且这种上转换发光强度随着Tm3 浓度的增强而降低, 但对应不同能级跃迁的发光强度降低的幅度不同, 这是因为Er3 和Tm3 之间的相互作用.     

AgNbO3拉曼光谱随激发功率变化的研究

AgNbO3是一种可见光响应型光催化剂, 具有简单的结构和化学组成, 以及合适的光学带隙, 并且在光催化分解水制氢和光催化降解有机污染物两方面具有较大的开发潜力。本文采用溶胶凝胶法合成了AgNbO3样品, 以457.5 nm固体激光器为激发光源, 首次在不同激发功率下, 获得了AgNbO3样品的拉曼谱图和谱峰参量随激光功率的变化关系。研究发现AgNbO3随激光功率的变化产生了可逆相变。     

多孔硅拉曼光谱随激发功率变化的研究

用阳极氧化法新制备了多孔硅样品,以457．5nm固体激光器为激发光源,在不同激发功率下,获得了拉曼谱图和一些谱峰参量随激光功率的变化关系。解释了520cm^-1和300cm^-1附近拉曼峰随功率变化的一系列可逆的实验现象：随激光功率升高出现的红移和非对称性展宽,主要是由于样品局域平均粒径变小而受量子限域效应的影响导致的;样品局域平均粒径在表面上的二维减小与随激光功率升高而导致的局域温升并不违背基本的热力学定律;高功率时520cm^-1附近双峰的出现是由于多孔硅样品局域平均粒径达到一定阈值而导致的纵模和横模双声子模的分裂。     

Special Features of Impulse Electronophotoluminescence

We consider special features of luminescence and its excitation on exposure of condensed substances to nanosecond beams of electrons with an energy of 100–300 keV at a peak power density exceeding 3·10⁶ W/cm². This kind of luminescence (iephluminescence) is excited in the absence of dynamic equilibrium between the electrons injected into the substance and leaving it. The depth of a brightly luminescing layer is an order of magnitude larger than the depth of penetration of electrons into the substance. The basic mechanism underlying the excitation of the impurity centers of luminescence in this layer of the substance is the radiative recombination of electron–hole pairs on impurity ions without a change of the ion charge. We show that the iefluminescence encompasses the positive qualities of electro, xray, photo, and cathodoluminescence. The high brightness and informativeness of the spectrum of iephluminescence allows the use of the latter for a fast nondestructive analysis of a substance.     

Concentration Dependence of NMR T1 in Agar Solutions

In this study, in order to explain solvent proton relaxation mechanism, the spin-lattice relaxation time (T1) of agar solutions was measured as a function of agar concentration. Relaxation measurements were carried out by a FT-NMR spectrometer operating at 60 MHz and inversion recovery pulse squence was used. Relaxation rate(1/T1a) was linearly proportional to concentration of agar solution (C), and the T1 mechanism of solvent water protons in agar solutions should be caused by the chemical exchange of water protons between free and bound water.