Rapid resolution of five polynuclear aromatic compounds in a mixture by derivative non-linear variable-angle synchronous fluorescence spectrometry

 A combination of non-linear variable-angle synchronous fluorescence spectrometry with the derivative technique has been developed. A rapid simultaneous identification and quantitative determination of acenaphthene, carbazole, anthracene, 9,10-dimethylanthracene and perylene were achieved from a single spectrum by non-linear variable-angle synchronous fluorescence and combined derivative non-linear variable-angle synchronous fluorescence. The latter approach offered a further improvement in spectral resolution and analytical sensitivity. The usefulness of the proposed method was confirmed by adding known amounts of these five polynuclear aromatic compounds to the extract of waste water samples. Received: 5 August 1996/Revised: 11 September 1996/Accepted: 14 September 1996     

Rapid resolution of five polynuclear aromatic compounds in a mixture by derivative non-linear variable-angle synchronous fluorescence spectrometry

 A combination of non-linear variable-angle synchronous fluorescence spectrometry with the derivative technique has been developed. A rapid simultaneous identification and quantitative determination of acenaphthene, carbazole, anthracene, 9,10-dimethylanthracene and perylene were achieved from a single spectrum by non-linear variable-angle synchronous fluorescence and combined derivative non-linear variable-angle synchronous fluorescence. The latter approach offered a further improvement in spectral resolution and analytical sensitivity. The usefulness of the proposed method was confirmed by adding known amounts of these five polynuclear aromatic compounds to the extract of waste water samples. Received: 5 August 1996/Revised: 11 September 1996/Accepted: 14 September 1996     

A novel approach for simultaneous determination of polycyclic aromatic hydrocarbons by Shpol'skii non-linear variable-angle synchronous fluorescence spectrometry

A new method of combining low-temperature Shpol'skii effect with non-linear variable-angle synchronous fluorescence spectrometry (L-NLVASFS) has been proposed to increase spectral resolution. This coupled method was applied successfully to the simultaneous identification and quantification of some polycyclic aromatic hydrocarbons (PAHs) in mixtures, which cannot be determined by non-linear variable-angle synchronous fluorescence spectrometry at room-temperature (R-NLVASFS). The usefulness of this method is demonstrated by the analyses of synthetic mixtures and several real samples of airborne particulates.     

Experimental estimation of fluorescence power efficiencies of several atoms in three turbulent flames used in atomic fluorescence flame spectrometry

An experimental system for the measurement of approximate atomic fluorescence power efficiencies of atoms in turbulent flames used in atomic fluorescence flame spectrometry is described. An expression is derived for the power efficiency as a function of instrumental parameters. Experimentally measured power efficiencies for eleven elements in fuel-rich oxyhydrogen, fuel-rich oxyacetylene, and fuel-rich hydrogen/argon/entrained air flames are given. The power efficiencies vary considerably from one spectral line to another, but as a result of the entrainment of ambient air into the turbulent flames, the values obtained in different flames are approximately equal. It is also shown that fluorescence radiation should rarely produce a significant error in atomic absorption spectrometry.     

Laser-excited ionic fluorescence spectrometry of rare-earth elements in the inductively-coupled plasma

A pulsed tunable dye laser pumped with an excimer laser is used to excite ionic fluorescence of the rare earth elements in the inductively-coupled plasma. Because several fluorescence lines were observed after laser excitation, it was possible to draw partial energy-level diagrams for most of the rare earths. Non-resonance fluorescence lines were used for all measurements in order to minimize spectral interferences. Detection limits at given excitation wavelengths are reported for each element. Laser-excited ionic fluorescence eliminates the problem of spectral interferences which has been associated with the determination of the rare earths by atomic emission spectrometry in the inductively-coupled plasma.     

A correction method of matrix,density and thickness effects in thin samples analysed by X-ray fluorescence spectrometry

This paper deals with X-ray fluorescence spectrometry of powdered materials deposited on collection filters. The general applicability of this method is limited because the spectral response is affected by sample density and thickness and interelement effects may occur due to the specimen composition.The present work is aimed at contributing to the solution of the above mentioned problems, and reports a mathematical correction method which changes fluorescence intensity measurement data into fluorescence intensity values free from density and thickness effects. The correction of the thickness effect was obtained by overlapping the powder sample with a standard pellet containing some reference elements.The method allows the evaluation of the thickness of the unknown samples by measuring the intensity decrease of the X-ray fluorescence radiation coming from the reference pellet and passing through the unknown sample. These data are used to correct the intensity fluorescence values of the unknown samples.A computer program to elaborate spectral data by means of different and selected mathematical algorithms was set up.     

Atomic fluorescence spectrometry with laser excitation

A laser atomic fluorescence spectrometry for the detection of trace concentrations of the elements is described. The detection limits for Pb, Fe, Na, Pt, Ir, Eu, Cu, Ag, Co and Mn in aqueous solutions obtained at present are the best ones for the rapid spectral analytical methods. The analytical potentials of the laser spectrometer are exemplified by the analysis of real samples of different chemical composition.     

Determination of lead in fly-ash from a garbage incinerator by atomic-absorption and x-ray fluorescence spectrometry

The lead content in fly-ash collected by an electrostatic precipitator has been determined by atomic-absorption spectrometry (AAS) after decomposition by four different leaching/dissolution techniques, and also determined by X-ray fluorescence spectrometry (XRFS) by the standard-addition method. The XRFS data were evaluated by non-linear regression since the standard additions affected the attenuation coefficient of the sample. Good agreement was obtained between the results obtained with AAS and XRFS. It is concluded that lead is quantitatively extracted by hot 1M nitric acid or treatment with hydrofluoric acid/nitric acid. Direct measurement of briquetted samples by XRFS is suggested for rapid monitoring of the lead content in fly-ash from garbage incineration.     

Coherent oscillations in ultrafast fluorescence of photoactive yellow protein

The ultrafast photoinduced dynamics of photoactive yellow protein in aqueous solution were studied at room temperature by femtosecond fluorescence spectroscopy using an optical Kerr-gate technique. Coherent oscillations of the wave packet were directly observed in the two-dimensional time-energy map of ultrafast fluorescence with 180 fs time resolution and 5 nm spectral resolution. The two-dimensional map revealed that four or more oscillatory components exist within the broad bandwidth of the fluorescence spectrum, each of which is restricted in the respective narrow spectral region. Typical frequencies of the oscillatory modes are 50 and 120 cm(-1). In the landscape on the map, the oscillatory components were recognized as the ridges which were winding and descending with time. The amplitude of the oscillatory and winding behaviors is a few hundred cm(-1), which is the same order as the frequencies of the oscillations. The mean spectral positions of the oscillatory components in the two-dimensional map are well explained by considering the vibrational energies of intramolecular modes in the electronic ground state of the chromophore. The entire view of the wave packet oscillations and broadening in the electronic excited state, accompanied by fluorescence transitions to the vibrational sublevels belonging to the electronic ground state, was obtained.     

Quantification in grazing-emission X-ray fluorescence spectrometry

In grazing-emission X-ray fluorescence (GEXRF) spectrometry wavelength-dispersive detection can be applied. Much softer radiation and hence lighter elements than in total-reflection X-ray (TXRF) spectrometry can thus be detected. We used simulations to investigate methods of quantification of GEXRF results involving soft characteristic radiation. From these studies, it is concluded that for ultra-thin layers, e.g. the sub-monolayer amounts encountered in semiconductor contamination analysis, calibration plots are linear. For thicker layers, quantification should be performed very carefully because of deviations from linearity due to absorption of radiation and to oscillations in the calibration curve. These oscillations are caused by interference of fluorescence radiation emitted directly towards the detector and radiation reflected at the sample–substrate interface. Suggestions for a judicious choice of measurement conditions are made and the benefits of internal standardisation are discussed.     

飞秒时间分辨荧光非共线光参量放大光谱技术

时间分辨荧光光谱技术是研究激发态弛豫、能量传递以及电荷转移等光化学过程的重要且直接的工具．飞秒时间分辨荧光非共线光参量放大光谱技术是一种新发展的具有高时间分辨率、宽探测带宽、高增益的时间分辨光谱技术．本文对该技术的基本原理与工作特性、系统配置、荧光收集和会聚、数据采集模式、时问分辨光谱数据处理等进行了系统阐述．最后简单介绍了飞秒时间分辨荧光非共线光参量放大光谱技术在物理、生物和化学领域的3个典型应用,并以此展现该技术的高时间分辨率、宽光谱探测及高增益优势．     

Silver nitrate chemical ionization for analysis of hydrocarbon polymers by laser desorption fourier transform mass spectrometry

Addition of silver nitrate to nonpolar hydrocarbon polymer solutions prior to their analysis by laser desorption Fourier transform mass spectrometry is shown to allow efficient silver ion chemical ionization. High-quality mass spectra are thus obtained for polymers, such as polystyrene, polyisoprene, polybutadiene, and polyethylene, that previously failed to yield useful mass spectra using conventional laser desorption. Accurate mass measurement experiments and isotopic ratios verify that the spectra are those of silver-attached oligomer ion distributions. Mass measurement errors for complete oligomer distributions average between 3 and 12 ppm for oligomers with masses between 400 and 6000 D whereas unit mass resolution is maintained throughout the entire spectral range.     

Grazing-emission X-ray fluorescence spectrometry; principles and applications

In grazing-emission X-ray fluorescence spectrometry (GEXRF), the sample is irradiated at approximately normal incidence, and only that part of the fluorescence radiation is detected that is emitted at grazing angles. This configuration allows the use of wavelength-dispersive detection. This type of detection has the advantages of substantially better energy resolution at longer wavelengths (light elements, L and M lines of heavier elements) and a much larger dynamic range than the energy-dispersive detectors currently used in grazing X-ray techniques. Typical examples are presented of applications that are made possible by this new technique.     

A boosted-output spectral lamp with interchangeable cathode for atomic fluorescence spectrometry

The new type of boosted-output atomic spectral lamp described has a readily-interchangeable cathode that requires only a small quantity of pure material. The direction of argon flow-through is designed to enable the lamp to be used with cathodes of relatively volatile elements such as arsenic and selenium, without the element being deposited on the exit window. The high numerical aperture of the lamp makes it suitable for use in atomic fluorescence spectrometry. Its warm-up time is faster than that of commercially-available electrodeless discharge lamps and its performance in flame atomic fluorescence at least as good. For less-volatile metals the performance is equal to that of earlier types of demountable boosted-output lamp.     

Evaluation of an inductively-coupled plasma with an extended-sleeve torch as an atomization cell for laser-excited fluorescence spectrometry

An inductively-coupled plasma (ICP) with an extended-sleeve torch has been evaluated as an atomization cell for laser-excited fluorescence spectrometry. Limits of detection for 20 lines are given. The detection power is almost equivalent to that obtained by excitation with a hollow-cathode lamp. Interelement effects and spectral interferences are discussed.     

X射线荧光光谱法结合多元统计学对热敏纸的检验研究

为建立一种快速且无损检验热敏纸的科学有效的方法,利用能量色散型X射线荧光光谱(XRF)对38个不同商家,不同规格的热敏纸样品进行检验,首先根据每个样品所测量得到的元素的不同,将38个样品分成四大类,同时采用SPSS25.0软件中的系统聚类法对38个样品的元素数据进行聚类分析处理,结果分成了12小组,再结合SPSS25.0软件中的判别分析法对上述结果进行验证,实现了基于X射线荧光光谱结合聚类分析建立数学模型用于区分热敏纸种类的目的,该方法简单易行,可以为案件侦破提供线索、指明方向。     

Characterization of cobalt pigments found in traditional Valencian ceramics by means of laser ablation-inductively coupled plasma mass spectrometry and portable X-ray fluorescence spectrometry

In this work, a comparison of the performances of laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) and portable X-ray fluorescence (XRF) spectrometry for the characterization of cobalt blue pigments used in the decoration of Valencian ceramics is presented. Qualitative data on the elemental composition of the blue pigments obtained using both techniques show a good agreement. Moreover, the results clearly illustrate that potters utilized different kinds of cobalt pigments in different historical periods.

While both techniques seem suitable for the proposed task, they show different strengths and weaknesses. Portable X-ray fluorescence spectrometry is a cheaper and totally non-destructive technique, capable of providing fast and reliable results at the mg g⁻¹ level. LA-ICPMS, on the other hand, offers a much higher detection power and better spatial resolution, but its use results in some sample damage (sample consumption at the μg level), while it is a more expensive and non-portable technique.     

Determination of the rare-earth elements in geological materials by thin-film X-ray fluorescence and inductively-coupled plasma atomic-emission spectrometry

Thin-film XRF and ICP-AES analytical procedures for the determination of the rare-earth elements (REE) in rocks, involving preconcentration by ion-exchange and co-precipitation with Fe(OH)(3) for thin-film preparation, and matrix modification, are described. The REE in five international reference rocks have been determined, with correction for spectral line overlap whenever necessary. The results obtained by using X-ray fluorescence spectrometry compare well with those of inductively-coupled plasma atomic-emission spectrometry, and with other values reported in the literature.     

Simultaneous determination of warfarin and bromadiolone by derivative synchronous fluorescence spectrometry

By using second derivative synchronous fluorescence spectrometry the simple resolution of mixtures of the anticoagulant rodenticides warfarin and bromadiolone in the presence of beta-cyclodextrin is accomplished which causes a differential effect on the fluorescence intensity of these compounds. The determination method developed is simple, fast and inexpensive; in addition, measurements are performed in a single scan. Mixtures of warfarin and bromadiolone in ratios between 4:1 and 1:10 were satisfactorily resolved.     

X射线荧光光光谱分析

评述了我国在2007～2008年X射线荧光光谱,包括质子激发的X射线光谱的发展和应用,内容包括仪器、软件、仪器改造、仪器维护和维修、基础研究和分析方法研究及其应用.