ISO-22309-2006.pdf

Reference number ISO 22309:2006(E) © ISO 2006 INTERNATIONAL STANDARD ISO 22309 First edition 2006-04-15 Microbeam analysis Quantitative analysis using energy-dispersive spectrometry (EDS) Analyse par microfaisceaux Analyse élémentaire quantitative par spectrométrie à sélection d'énergie (EDS) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. 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ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii © ISO 2006 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) © ISO 2006 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references. 2 3 Terms and definitions. 2 4 Specimen preparation 6 5 Preliminary precautions. 7 6 Analysis procedure. 7 7 Data reduction. 9 7.1 General. 9 7.2 Identification of peaks 9 7.3 Estimation of peak intensity 9 7.4 Calculation of k-ratios 10 7.5 Matrix effects. 10 7.6 Use of reference materials. 10 7.7 Standardless analysis 11 7.8 Uncertainty of results. 11 7.9 Reporting of results 12 Annex A (informative) The assignment of spectral peaks to their elements. 14 Annex B (informative) Peak identity/interferences . 16 Annex C (informative) Factors affecting the uncertainty of a result. 18 Annex D (informative) Analysis of elements with atomic number 10. Guidance on the analysis of light elements with Z 10) in the specimen, its concentration can be determined by summing the appropriate proportions of concentrations of the other elements. This is often used for the analysis of oxygen in silicate mineral specimens. c) Calculation of concentration by difference where the light element percentage is 100 % minus the percentage sum of the analysed elements. This method is only possible with good beam-current stability and a separate measurement of at least one reference specimen and it requires very accurate analysis of the other elements in the specimen. Annex D summarises the problems of light element analysis, additional to those that exist for quantitative analysis of the heavier elements. If both EDS and wavelength spectrometry (WDS) are available, then WDS can be used to overcome the problems of peak overlap that occur with EDS at low energies. However, many of the other issues are common to both techniques. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) 2 © ISO 2006 All rights reserved 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 14594, Microbeam analysis Electron probe microanalysis Guidelines for the determination of experimental parameters for wavelength dispersive spectroscopy ISO 15632:2002, Microbeam analysis Instrumental specification for energy dispersive X-ray spectrometers with semiconductor detectors ISO 16700:2004, Microbeam analysis Scanning electron microscopy Guidelines for calibrating image magnification ISO/IEC 17025:2005, General requirements for the competence of testing and calibration laboratories 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 absorption correction matrix correction arising from the loss of X-ray intensity from an element due to photoelectric absorption by all elements within the specimen while passing through it to the detector 3.2 accuracy closeness of agreement between the “true” value and the measured value 3.3 accelerating voltage potential difference applied between the filament and anode in order to accelerate the electrons emitted from the source NOTE Accelerating voltage is expressed in kilovolts. 3.4 atomic number correction matrix correction which modifies intensity from each element in the specimen and standards to take account of electron backscattering and stopping power, the magnitudes of which are influenced by all the elements in the analysed volume 3.5 beam current electron current contained within the beam NOTE Beam current is expressed in nanoamperes. 3.6 beam stability extent to which beam current varies during the course of an analysis NOTE Beam stability is expressed in percent per hour. 3.7 bremsstrahlung background continuum of X-rays generated by the deceleration of electrons within the specimen Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) © ISO 2006 All rights reserved 3 3.8 certified reference material CRM reference material, one or more of whose property values are certified by a technically valid procedure, accompanied by or traceable to a certificate or other documentation which is issued by a certifying body 3.9 characteristic X-ray photon of electromagnetic radiation created by the relaxation of an excited atomic state caused by inner shell ionisation following inelastic scattering of an energetic electron, or by absorption of an X-ray photon 3.10 dead time the time that the system is unavailable to record a photon measurement because it is busy processing a previous event NOTE This is frequently expressed as a percentage of the total time (see also live time). 3.11 energy-dispersive spectrometry EDS form of X-ray spectrometry in which the energy of individual photons are measured and used to build up a digital histogram representing the distribution of X-rays with energy 3.12 electron probe microanalysis a technique of spatially resolved elemental analysis based on electron-excited X-ray spectrometry with a focused electron probe and an interaction/excitation volume with micrometre to sub-micrometre dimensions 3.13 escape peaks peaks that occur as a result of loss of incident photon energy by fluorescence of the material of the detector NOTE 1 These occur at an energy equal to that of the incident characteristic peak minus the energy of the X-ray line(s) emitted by the element(s) in the detector (1,734 keV for silicon). NOTE 2 They cannot occur below the critical excitation potential of the detector material, e.g. Si K escape does not occur for energies below 1,838 keV. 3.14 fluorescence photoelectric absorption of any X-ray radiation (characteristic or bremsstrahlung) by an atom which results in an excited atomic state which will de-excite with electron shell transitions and subsequent emission of an Auger electron or the characteristic X-ray of the absorbing atom 3.15 fluorescence correction matrix correction which modifies the intensity from each element in the specimen and standards to take account of excess X-rays generated from element “A” due to the absorption of characteristic X-rays from element “B” whose energy exceeds the critical (ionisation) energy of “A” 3.16 full width at half maximum FWHM measure of the width of an X-ray peak in which the background is first removed to reveal the complete peak profile NOTE FWHM is determined by measuring the width at half the maximum height. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) 4 © ISO 2006 All rights reserved 3.17 incident beam energy energy gained by the beam as a result of the potential applied between the filament and anode 3.18 k-ratio net peak intensity (after background subtraction) for an element found in the specimen, divided by the intensity, recorded or calculated, of the corresponding peak in the spectra of a reference material 3.19 live time (s) time the pulse measurement circuitry is available for the detection of X-ray photons See also dead time (3.10). NOTE 1 Live time is expressed in second (s). NOTE 2 Live time = real time for analysis dead time. Real time is the time that would be measured with a conventional clock. For an X-ray acquisition, the real time always exceeds the live time. 3.20 overvoltage ratio ratio of the incident beam energy to the critical excitation energy for a particular shell and sub-shell (K, LI, LII, etc.) from which the characteristic X-ray is emitted 3.21 peak intensity total number of X-rays (counts) under the profile of a characteristic X-ray peak after background subtraction NOTE This is sometimes referred to as the peak integral. 3.22 peak profile detailed shape of a characteristic peak which depends on the relative intensities and energies of the individual X-ray emissions that are unresolved by the energy-dispersive spectrometer 3.23 precision closeness of agreement between the results obtained by applying the experimental procedure several times under prescribed conditions 3.24 quantitative EDS procedure leading to the assignment of numerical values or expressions to represent the concentrations of elements measured within the analysis volume 3.25 reference material RM material or substance, one or more properties of which are sufficiently well established to be used for the calibration of an apparatus, the assessment of a method, or for assigning values to materials NOTE A reference material is said to be homogeneous with respect to a specified property if the property value, as determined by tests on specimens of specified size, is found to lie within the specified uncertainty limits, the specimens being taken either from a single or different supply unit. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) © ISO 2006 All rights reserved 5 3.26 repeatability closeness of agreement between results of successive measurements of the same quantity carried out by the same method, by the same observer, with the same measuring instruments, in the same laboratory, at quite short intervals of time 3.27 reproducibility closeness of agreement between the result of measurements of the same quantity, where the individual measurements are made by different methods, with different measuring instruments, by different observers, in different laboratories, after intervals of time that are quite long compared with the duration of a single measurement, under different normal conditions of use of the instruments employed 3.28 resolution energy width of a peak measured by an energy-dispersive spectrometer and expressed as the peak width at half the maximum peak intensity NOTE This is usually expressed as the value for Mn K (5,894 keV), although peaks from other suitable elements can be used. 3.29 resolution spatial spatial specificity of microanalysis NOTE This is usually expressed in terms of a linear or volumetric measure of the region of the specimen that is sampled by the measured characteristic radiation. 3.30 standardless analysis procedure for quantitative X-ray microanalysis in which the reference peak intensity in the k-value expression, (unknown/reference) is supplied from purely physical calculations or from stored data from a suite of reference materials; adjustments being made to match analysis conditions and augment incomplete reference data 3.31 sum peaks artefact peaks that occur as a result of pulse co-incidence effects that occur within the pulse pair resolution of the pile-up inspection circuitry NOTE These peaks appear at energies corresponding to the sum of those energies of the two photons that arrive simultaneously at the detector. 3.32 traceability ability to trace the history, application or location of an entity by means of recorded identifications 3.33 uncertainty that part of the expression of the result of a measurement that states the range of values within which the “true” value is estimated to lie for a stated probability 3.34 validation confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use are fulfilled 3.35 X-ray absorption attenuation of X-rays passing through matter, arising primarily from photoelectric absorption for X-ray energies and ranges appropriate to EPMA/EDS and SEM/EDS Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/16/2007 09:06:15 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 22309:2006(E) 6 © ISO 2006 All rights reserved 4 Specimen preparation 4.1 Material for analysis shall be stable under variable pressure conditions and the electron beam. As- received specimens can be examined af