Investigations on the use of pneumatic cross-flow nebulizers with dual solution loading including the correction of matrix effects in elemental determinations by inductively coupled plasma optical emission spectrometry

The use of a so-called trihedral and a T-shaped cross-flow pneumatic nebulizer with dual solution loading for inductively coupled plasma optical emission spectrometry has been studied. By these devices analyte clouds from two solutions can be mixed during the aerosol generation step. For both nebulizers the correction of matrix effects using internal standardization and standard addition calibration in an on-line way was investigated and compared to elemental determinations using a conventional cross-flow nebulizer and calibration with synthetic standard solutions without matrix matching. A significant improvement of accuracy, both for calibration with internal standardization and standard addition, was obtained in the case of four synthetic solutions containing each 40 mmol L^− 1 Na, K, Rb and Ba as matrix elements and 300 μg L^− 1 Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb as analytes. Calibration by standard addition in the case of dual solution loading has been shown to be very useful in the determination of elements at minor and trace levels in steel and alumina reference materials. The results of analysis for minor concentrations of Cr, Cu and Ni in steel as well as for Ca, Fe, Ga, Li, Mg, Mn, Na, Si and Zn in alumina powder certified reference materials subsequent to sample dissolution were found to be in good agreement with the certificates. Limits of detection were found to be only slightly above those for a conventional cross-flow nebulizer and a precision better than 3% was realized with both novel nebulizers.     

微波等离子体炬发射光谱法去溶系统性能的研究

用微波等离子体矩（MPT）作激发光源，等离子体的工作气体为氩气，研究了气动雾化进样去溶系统的工作参数对分析性能的影响，探讨了水冷凝与浓硫酸吸收二者协同去溶的相关性，结果表明，OH （Q1带，带头谱线为308.520nm）的发射强度即可判别样品去溶效果。     

Sr／Ca比变化对红色荧光粉Ca1-xSrxS：Eu^2＋的影响

在CO气氛下采用固相反应法合成了发红光的Ca1-xSrxS:Eu^2 荧光粉，研究了基质阳离子Sr／Ca比变化对其晶体性质及发光性能的影响。结果表明，随着Sr／Ca比的减少，荧光粉的晶胞参数逐渐降低；同时，由于受电子云膨胀效应和晶体场影响，发射主峰向长波方向移动，红色比逐渐增大，色纯度提高。     

Influence of substrate morphology on organic layer growth: PTCDA on Ag(1 1 1)

By UV-excited photoelectron emission microscopy (UV-PEEM) we investigated the microscopic growth behavior of organic thin films using 3,4,9,10-perylene-tetracarboxylicacid dianhydride (PTCDA) on a Ag(1 1 1) single crystal substrate as example. Direct, real time observation allows to correlate the initial growth modes and the related kinetic parameters with substrate properties like terrace width, step density, and step bunches from the submonolayer range up to 5 layers or more. Above room temperature PTCDA grows in a Stranski–Krastanov fashion: after completion of the first two stable layers three-dimensional islands are formed. The nucleation density strongly depends on the temperature and the substrate morphology thus affecting the properties of the organic film.     

电感耦合等离子体原子发射光谱专家系统中谱线激发模型

阐述了ＩＣＰ－ＡＥＳ专家系统中ＡＥＳ电离和激发模型的基本原理，研究了模拟中应用ｎｏｎ－ＬＴＥ理论的正确性以及所需的支持数据库。利用Ｂｏｌｔｚｍａｎｎ曲线，讨论了Ｂｏｌｔｚｍａｎｎ温度的测量值随能级激发能变化的现象，并与类似条件下的经验Ｂｏｌｔｚｍａｎｎ曲线进行对比，证明了专家系统中ＡＥＳ电脑和激发模型可靠性。     

Analysis of microgram amounts of particulate material by simultaneous multiwavelength AES

A unique simultaneous emission spectrograph is utilized to perform qualitative and quantitative analysis on trace quantities of solid particulates. The atomic emission spectroscopic system consists of a direct current plasma source and an echelle spectrograph with a charge injection device detector, enabling the system to simultaneously measure the wavelength range from 220 nm to 520 nm with 0.02 nm resolution at 300 nm. Monitoring all wavelengths simultaneously allows the qualitative and quantitative determination of most major and minor constituent in a trace quantity of sample with little prior knowledge about the sample. The ability to perform qualitative and quantitative analysis on particulates is demonstrated by evaluating NBS certified coal fly ash, as well as a sample taken from the respirator air filter at an acute care unit in a hospital.Presented in part at the 1989 European Winter Conference on Plasma Spectrochemistry, Reutte, Austria     

Synthesis and Opto-Electronic Properties of Cholesteric Cellulose Esters

Cholesteric materials display unique optical properties which can be exploited in opto-electronic applications such as light emitting diodes. The key feature is the position of the wavelength of the emitted light relative to the one of the selective reflection band. We have synthesized a set of cellulose derivatives displaying the cholesteric phase with the aim to investigate the correlation between chemical structure and properties. Phase transition temperatures, the chain packing, the wavelength of selective reflection but also absorption and fluorescence spectra were investigated as a function of the degree of substitution (DS), the nature of lateral substituents, the composition of doped systems and blends of different cellulose derivatives. Investigated were furthermore the degree of circular polarization of the emitted light for guest–host systems and for cellulose systems with chromophores linked by covalent bonds to the cellulose backbone as well as their performance in light emitting diodes. The conclusion is that the optical properties can be accounted for on the basis of the model of a one-dimensional photonic crystal. The limiting factor with respect to opto-electronic applications is the poor control of the uniformity of the helix formation and orientation.     

Study of reactive ion etching of Si and SiO2 for CFxCl4−x gases

A parametric study of the etching of Si and SiO₂ by reactive ion etching (RIE) was carried out to gain a better understanding of the etching mechanisms. The following fluorocarbons (FCs) were used in order to study the effect of the F-to-Cl atom ratio in the parent molecule to the plasma and the etching properties: CF₄, CF₃Cl, CF₂Cl₂, and CFCl₃ (FC-14, FC-13, FC-12, and FC-11 respectively). The Si etch rate uniformity across the wafer as a function of the temperature of the wafer and the Si load, the optical emission as a function of the temperature of the load, the etch rate of SiO₂ as a function of the sheath voltage, and the mass spectra for each of the FCs were measured. The temperature of the wafer and that of the surrounding Si load strongly influence the etch rate of Si, the uniformity of etching, and the optical emission of F, Cl, and CF₂. The activation energy for the etching reaction of Si during CF₄ RIE was measured. The etch rate of Si depends more strongly on the gas composition than on the sheath voltage; it seems to be dominated by ion-assisted chemical etching. The etching of photoresist shifted from chemical etching to ion-assisted chemical etching as a function of the F-to-Cl ratio and the sheath voltage. The etch rate of SiO₂ depended more strongly on the sheath voltage than on the F-to-Cl ratio.     

Characterization and determination of 28 elements in fly ashes collected in a thermal power plant in Argentina using different instrumental techniques

Different techniques were selected for comprehensive characterization of seven samples of fly ashes collected from the electrostatic precipitator of the San Nicolás thermal power plant (Buenos Aires, Argentina). Particle size was measured using laser based particle size analyzer. X-ray diffraction powder (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the mineral phase present in the matrix consisting basically of aluminosilicates and large amounts of amorphous material. The predominant crystalline phases were mullite and quartz. Major and minors elements (Al, Ca, Cl, Fe, K, Mg, Na, S, Si and Ti) were detected by energy dispersive X-ray analysis (EDAX). Trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, V and Zn) content was quantified by inductively coupled plasma optical emission spectrometry (ICP OES). Different acid mixtures and digestion procedures were compared for subsequent ICP OES measurements of the dissolved samples. The digestion procedures used were: i) a mixture of FH + HNO₃ + HClO₄ (open system digestion); ii) a mixture of FH + HNO₃ (MW-assisted digestion); iii) a mixture of HF and aqua regia (MW-assisted digestion). Instrumental neutron activation analysis (INAA) was employed for the determination of As, Ba, Co, Cr, Ce, Cs, Eu, Fe, Gd, Hf, La, Lu, Rb, Sb, Sc, Sm, Ta, Tb, Th, U and Yb. The validation of the procedure was performed by the analysis of two certified materials namely, i) NIST 1633b, coal fly ash and ii) GBW07105, rock. Mean elements content spanned from 41870 μg g^− 1 for Fe to 1.14 μg g^− 1 for Lu. The study showed that Fe (41870 μg g^− 1) ? V (1137 μg g^− 1) > Ni (269 μg g^− 1) > Mn (169 μg g^− 1) are the main components. An enrichment, with respect to crustal average, in many elements was observed especially for As, V and Sb that deserve particular interest from the environmental and human health point of view.     

Emission,Emissionslebensdauer und Absorption von [Cr urea6]X3-Einkristallen

Emission and absorption polarization spectra as well as emission lifetimes between room temperature and 5 °K have been measured of [Cr urea₆]X₃ single crystals, where X stands for ClO ₄ ^– , J^–, NO ₃ ^– , Br^–, Cl^–, F^–, and X₃ for JSO ₄ ^3– . The strong temperature dependence of the fluorescence/phosphorescence-ratios, and of the emission lifetimes is discussed. The differences between the spectra as well as the emission lifetimes of the various salts can be attributed to an anion dependent trigonal perturbation.

Die Autoren danken dem Verband der Chemischen Industrie für finanzielle Unterstützung dieser Arbeit.