BS ISO 14594-2014 Microbeam analysis Electron probe microanalysis Guidelines for the determination of experimental parameters for wavelength dispersive spectroscopy《微电子束分析 电子探测微观分析.pdf

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1、BSI Standards PublicationBS ISO 14594:2014Microbeam analysis Electron probe microanalysis Guidelines for thedetermination of experimentalparameters for wavelengthdispersive spectroscopyBS ISO 14594:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 14594:2014

2、. It supersedes BS ISO 14594:2003 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee CII/9, Microbeam analysis.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include a

3、ll the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 86898 6ICS 71.040.50Compliance with a British Standard cannot confer immunity from legal obligations.This British

4、 Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2014.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 14594:2014 ISO 2014Microbeam analysis Electron probe microanalysis Guidelines for the determination of exper

5、imental parameters for wavelength dispersive spectroscopyAnalyse par microfaisceaux Analyse par microsonde lectronique (Microsonde de Castaing) Lignes directrices pour la dtermination des paramtres exprimentaux pour la spectromtrie dispersion de longueur dondeINTERNATIONAL STANDARDISO14594Second edi

6、tion2014-10-15Reference numberISO 14594:2014(E)BS ISO 14594:2014ISO 14594:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, elect

7、ronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 4

8、1 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 14594:2014ISO 14594:2014(E) ISO 2014 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 13 Terms and definitions . 14 Abbreviated terms 25 Experimental parameters . 2

9、5.1 General . 25.2 Parameters related to the primary beam . 25.3 Parameters related to wavelength dispersive X-ray spectrometers . 35.4 Parameters related to the specimen . 46 Procedures and measurements 56.1 General . 56.2 Beam current 56.3 Parameters related to measured peaks . 66.4 Parameters rel

10、ated to the specimen . 87 Test report . 9Annex A (informative) Methods of estimating analysis area 10Annex B (informative) Methods of estimating analysis depth 12Annex C (informative) Method of estimating X-ray analysis volume by applying the Monte Carlo (MC) simulation 14Bibliography .18BS ISO 1459

11、4:2014ISO 14594:2014(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a

12、 subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commissio

13、n (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should

14、 be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for ident

15、ifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenie

16、nce of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - S

17、upplementary informationThe committee responsible for this document is ISO/TC 202, Microbeam analysis, Subcommittee SC 2, Electron probe microanalysis.This second edition cancels and replaces the first edition (ISO 14594:2003), of which it constitutes a minor revision. It also incorporates the Techn

18、ical Corrigendum ISO 14594:2003/Cor 1:2009.iv ISO 2014 All rights reservedBS ISO 14594:2014INTERNATIONAL STANDARD ISO 14594:2014(E)Microbeam analysis Electron probe microanalysis Guidelines for the determination of experimental parameters for wavelength dispersive spectroscopy1 ScopeThis Internation

19、al Standard gives the general guidelines for the determination of experimental parameters relating to the primary beam, the wavelength spectrometer, and the sample that need to be taken into account when carrying out electron probe microanalysis. It also defines procedures for the determination of b

20、eam current, current density, dead time, wavelength resolution, background, analysis area, analysis depth, and analysis volume.This International Standard is intended for the analysis of a well-polished sample using normal beam incidence, and the parameters obtained can only be indicative for other

21、experimental conditions.This International Standard is not designed to be used for energy dispersive X-ray spectroscopy.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, onl

22、y the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO/IEC 17025:2005, General requirements for the competence of testing and testing laboratories3 Terms and definitionsFor the purposes of this document, the following

23、 terms and definitions apply.3.1analysis areatwo-dimensional region of sample surface from which the full signal or a specified percentage of that signal is detected3.2analysis depthdistance from the sample surface to the bottom normal to the surface from which the full signal or a specified percent

24、age of that signal is detected3.3analysis volumethree-dimensional region of a sample from which the full signal or a specified percentage of that signal is detected3.4backgroundnon-characteristic component of an X-ray spectrum arising from the X-ray continuum3.5beam currentelectron current contained

25、 within the focused beam ISO 2014 All rights reserved 1BS ISO 14594:2014ISO 14594:2014(E)3.6beam current densitybeam current incident on the sample per unit area3.7dead timetime associated with the measurement of a signal photon in a detector and/or counting system, representing the time that the sy

26、stem is unavailable to process the next photon3.8wavelength resolutionfull peak width at half maximum of a characteristic X-ray peak4 Abbreviated termsEPMA Electron Probe MicroanalysisFWHM Full Width at Half MaximumWDX Wavelength Dispersive X-ray5 Experimental parameters5.1 GeneralThe parameters giv

27、en in 5.2.1, 5.2.3, and 5.2.4 should be known and recorded. Checking the calibration of beam energy, beam current, and magnification together with counter dead time should be included in the maintenance schedule of the instrument.5.2 Parameters related to the primary beam5.2.1 Beam energyThe beam en

28、ergy typically ranges from 2 keV to 30 keV. In most cases, the calibration of the beam energy is not critical for qualitative analysis.NOTE Calibration is very critical in the case of use of low overvoltage ratio or during measurements relating to layer thickness or elemental depth distributions.5.2

29、.2 Beam currentBecause X-ray peak intensity is directly proportional to beam current, the precision of the measurement of the beam current should be better than the precision required for quantitative analysis.The beam current stability over long periods of time is absolutely essential for consisten

30、t quantitative analysis. The beam current stability should be tested periodically, especially prior to quantitative calibration and analysis. It is possible to compensate for small changes in beam current if this is recorded prior to and following each measurement. Then all X-ray peak and background

31、 measurements should be scaled appropriately by Ii/Im,where Iiis the initial beam current and Imis the beam current at the time of the measurement.5.2.3 Beam current densityBeam current density is especially important when analyzing beam sensitive materials. The current density in a focused probe ca

32、n exceed 104A m-2. The effective current density can be reduced for a measurement by lowering the incident electron beam current or, where lateral resolution is not critical, 2 ISO 2014 All rights reservedBS ISO 14594:2014ISO 14594:2014(E)by either defocusing or rastering the probe. If a rastered pr

33、obe is used, a similar scan should be used for comparative measurements on standards and other specimens because the effective spectrometer efficiency for the selected wavelength decreases as a function of the beam deflection. See 5.3.5.5.2.4 MagnificationTo properly define the dimensional scale for

34、 line-scans and images acquired by deflecting the primary electron beam, it is essential to calibrate the magnification scale while operating in the scanning electron mode.5.3 Parameters related to wavelength dispersive X-ray spectrometers5.3.1 GeneralAn instrument may be fitted with one or more WDX

35、 spectrometers, each with a number of diffracting crystals that may be selected to cover a particular range of X-ray wavelengths depending on the line of the analysed element. The following parameters are important for the proper operation of WDX spectrometers.5.3.2 Take-off angleThe take-off angle

36、affects quantitative analysis. Any comparison of measurements from instruments with different take-off angles should be taken into account and the procedures used be noted in the analysis report.NOTE The value of this angle, which is normally fixed, is provided by the instrument manufacturer.5.3.3 W

37、avelength resolutionThe spectral resolution depends on the following parameters: crystal material (and Miller indices of the crystal planes); the radius of curvature of the diffracting crystal (fully focusing vs. semi-focusing crystal); the presence of a crystal mask (if semi-focusing crystal); the

38、size and position of the counter entrance window or of the entrance slit if present.All these settings determine the wavelength resolution of the measured X-ray spectrum and the observed line-width (FWHM) of the characteristic X-ray peaks.Resolution can also influence the ability of the system to di

39、scriminate against overlapping peaks, background signals, and the sensitivity of measurements to specimen height and beam position on the specimen.5.3.4 X-ray detector and counting chainMany spectrometers use a gas-filled proportional counter to detect X-rays. The magnitude of the output pulses from

40、 these detectors is determined by the incident X-ray energy and/or the voltage applied to the counters. Two discriminators are used to select the pulse of interest. A low discriminator setting is used to eliminate pulses due to noise, while a high discriminator setting excludes pulses from high orde

41、r reflections of more energetic X-rays. Optimum settings depend on the X-ray lines of interest.It is important to set the discriminator to ensure that any unintended shift in pulse amplitude, for example, due to high count rates or changes in atmospheric temperature and pressure (flow counter), has

42、no significant effect on the measured count rate.Because X-ray counting efficiency decreases with increasing count rate, it is important to correct the measured count rate for the effect of the dead time. In an automated system, the discriminator settings ISO 2014 All rights reserved 3BS ISO 14594:2

43、014ISO 14594:2014(E)can be set automatically. These settings should be routinely checked to ensure proper automatic operation.5.3.5 Peak location (wavelength)Under normal circumstances, the wavelength which has the maximum peak intensity is used to define the location of an X-ray peak. It is necessa

44、ry, using suitable reference materials, to periodically check and correct for the difference in a peaks theoretical position and its actual measured position on a given spectrometer and diffraction crystal. The time between checks will depend on the stability of the instrument spectrometers.The meas

45、ured maximum intensities of peaks which have narrow FWHM values are strongly affected by the errors in peak location. The peak intensity can be changed due to the chemical state and polarization effects.NOTE 1 If the element in the sample of interest is in a different chemical state than that of the

46、 reference material, then the shape of the characteristic X-ray peak might be different for specimen and standard. In this case, the peak maximum might not provide a reliable measure of the total peak intensity and an alternative approach, such as peak area measurements, might be required to obtain

47、reliable results. These chemical state effects are particularly important for X-ray peaks with low energy values.NOTE 2 If a crystalline sample causes the polarization effects in relation to the position between the sample and the analysis crystal, the peak shape and location can be changed. This ca

48、n be checked by rotating the sample around an axis perpendicular to the electron beam and observing the effect on peak shape and location. The problem might occur in systems with symmetry lower than cubic and higher than triclinic and is worst when the Bragg angle is close to 45. The phenomenon has

49、been found in graphite1and certain borides.2The effect can be much reduced by using peak area measurements.The position of the peak maximum varies with deviation of the probe from the focal point of the spectrometer on the sample. Calibration measurements and quantitative analysis on the sample should normally be made with the probe in the same position relative to this focal point, and using the same beam defocus or raster setting, if applied. For all quantitative and qualitative analyses carried out using a defocused and scanned b