Polyol-mediated synthesis of water-soluble LaF3:Yb,Er upconversion fluorescent nanocrystals

Well-crystallized LaF₃:Yb,Er nanoparticles were prepared by the polyol method and three kinds of polyols (glycol, diethylene glycol and glycerol) were chosen as the reaction medium respectively. All of the obtained LaF₃:Yb,Er nanoparticles have roughly spherical shapes, and the average sizes of these nanoparticles ranged from 5 to 7 nm. These nanoparticles could be well dispersed in water or ethanol to form colloidal solutions. When these nanoparticles were excited by the 980 nm laser, several upconversion emissions were observed.     

Extracting Electron Densities in N-Type GaAs From Raman Spectra: Theory

In this paper, we present the theory for calculating Raman line shapes as functions of the Fermi energy and finite temperatures in zinc blende, n-type GaAs for donor densities between 10¹⁶ cm⁻³ and 10¹⁹ cm⁻³. Compared to other theories, this theory is unique in two respects: 1) the many-body effects are treated self-consistently and 2) the theory is valid at room temperature for arbitrary values of the ratio R = (Q²/α), where Q is the magnitude of the normalized wave vector and α is the normalized frequency used in the Raman measurements. These calculations solve the charge neutrality equation self-consistently for a two-band model of GaAs at 300 K that includes the effects of high carrier concentrations and dopant densities on the perturbed densities of states used to calculate the Fermi energy as a function of temperature. The results are then applied to obtain the carrier concentrations from Fermi energies in the context of line shapes in Raman spectra due to the coupling between longitudinal optical phonons and plasmons. Raman measurements have been proposed as a non-destructive method for wafer acceptance tests of carrier density in semiconductor epilayers. The interpretation of Raman spectra to determine the majority electron density in n-type semiconductors requires an interdisciplinary effort involving experiments, theory, and computer-based simulations and visualizations of the theoretical calculations.     

理学SMX-10/11型X荧光光谱仪的改进

对理学SMX-10／ll型X荧光光谱仪真空系统、样品定位系统及热交换器冷却水循环路径等易发生故障部位进行改进，并在11型仪器上增加了S元素分析通道。生产应用表明，改进效果良好，简化了分析工艺。降低了分析成本，提高了仪器的稳定性。     

源气体流量比对F-DLC薄膜结构的影响

以高纯石墨作靶，CHF3/Ar作源气体采用反应磁控溅射法制备出了氟化类金刚石（F-DLC）薄膜。拉曼光谱表明，CHF3相对流量的增加会引起薄膜的D峰与G峰强度之比I（D）/I（G）减小，晶粒增大，芳香环结构出例下降。红外吸收光谱分析证实了这些推论，指出这是由于薄膜中氟含量上升的结果。     

用RAFA方法定量解析芳烃混合物的EEM

本文介绍了降秩因子分析(RAFA)方法,它是从一个多组分混合物中直接定量计算其中某一组分,而不必知道其它组分的物种及含量的一种定量分析的数学方法。它适用于双线性的数据。本实验首先将荧光分光光度计与外接计算机相连,以获得样品的激发-发射矩阵(EEM),再用RAFA方法对蒽、萘、菲、芘、芴、(艹屈)六种标样的一至五组分的混合物进行定量分析,获得满意的结果。     

Studies of photoconductivity in β-Apo-8′ carotenal

The photoconductive properties of a carotenoid polyene,β-Apo-8′ carotenal in polycrystalline form has been studied. The growth of the photocurrent shows an overshoot in the growth-time curve before steady state value is attained. This behaviour of photocurrent is proposed to be due to higher value of recombination coefficient than trapping coefficient. From the temperature dependence study it is observed that the steady state photocurrent, at first increases with increase of temperature, attains a maximum at a particular temperatureT _max and then decreases with temperature. TheT _max value agrees with the temperature above and below which steady state photocurrent is attained differently. Monomolecular and bimolecular recombination processes at two temperature regimes are proposed to account for the observed behaviour. The dependence of photocurrent with excitation light intensity and wavelength study provide information on the carrier generation processes. The fast decay of photocurrent have been observed at different temperatures and from this study the decay constant is calculated and it is found to be temperature independent.     

GaP：（N）的背景光谱和发光尖峰

获得高分辨ＧａＰ（Ｎ）光致发光光谱，观察到等电子陷陆束缚激子发光中ＬＯ和ｌｏｃ多声子发射，其强度分布答合泊松分布。将声子伴带区分为直接光跃迁和间接光跃迁，并进行了相应讨论，还观察到局域声子效应－－光谱相似定律和相当显著的背景光谱。     

Standard reference materials for cements

The eight portland cements and two calcium aluminate cements in the Standard Reference Material (SRM) 1880 series are among the most popular SRMs in the catalog of the National Institute of Standards and Technology (NIST) Standard Reference Materials Program. Numerous laboratories rely on them for elemental analysis and qualification for ASTM C 114-00 Standard Test Methods for Chemical Analysis of Hydraulic Cement. NIST has collected new candidate materials from around the world and partnered with Construction Technology Laboratories (CTL) in their preparation and certification. This paper describes the procedures taken at NIST and CTL to prepare and test materials for certification including the homogeneity testing, the X-ray fluorescence methods and the statistical data analysis performed for value assignment.     

New method for measuring an optical property of a sample treated by FWA

In this article, a new method for measuring a total spectral radiance factor of a FWA‐treated sample illuminated by a specific standard illuminant is introduced. The method replaces an unstable real fluorescent standard by a bi‐spectral luminescent radiance factor data, which works as a virtual fluorescent standard (VFS) by knowing spectral intensity distributions of illuminations applied to the sample. The method utilizes two illuminations I₁ and I₂ whose relative spectral intensity distributions are different from each other and synthesizes a virtual illumination presenting the identical fluorescent spectral radiance factor to that presented by the standard illuminant with the VFS of the specific bi‐spectral luminescent radiance factor by linearly combining I₁ and I₂ with the suitable weighting factors. The applicability of the method is examined in principle by comparing ISO brightness and CIE whiteness index of fluorescent standard paper as a test sample obtained by this new method to the assigned values. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 195–200, 2007     

New HPLC Method to Determine Ethyl Carbamate in Alcoholic Beverages Using Fluorescence Detection

ABSTRACT: A new methodology to the quantification of ethyl carbamate (EC) has been developed. This method allows the analysis by HPLC of ethyl carbamate in samples of wine, fortified wine, and wine brandy, by a pre-column derivatization with 9-xanthydrol, and fluorescence detection. This does not require previous sample extraction or concentration. The method presents an average recovery of 96% among samples studied, a detection limit of 4.2μg/L, and an average intermediate precision of 6.3%. The comparison of the results obtained for EC analysis on the same wine brandy samples by GC/MS and HPLC are statistically indistinguishable with 97.5% probability. The results of the analysis of 42 samples are presented.