BS ISO 23830-2008 Surface chemical analysis - Secondary-ion mass spectrometry - Repeatability and constancy of the relative-intensity scale in static secondary-ion mass spectrometr.pdf

1、BS ISO23830:2008ICS 71.040.40NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDSurface chemicalanalysis Secondary-ion mass spectrometry Repeatability andconstancy of therelative-intensity scalein static secondary-ionmass spectrometryThis British Standardwas publis

2、hed under theauthority of the StandardsPolicy and StrategyCommittee on 31 December2008 BSI 2008ISBN 978 0 580 55766 8Amendments/corrigenda issued since publicationDate CommentsBS ISO 23830:2008National forewordThis British Standard is the UK implementation of ISO 23830:2008.The UK participation in i

3、ts preparation was entrusted to TechnicalCommittee CII/60, Surface chemical analysis.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its

4、correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS ISO 23830:2008Reference numberISO 23830:2008(E)ISO 2008INTERNATIONAL STANDARD ISO23830First edition2008-11-15Surface chemical analysis Secondary-ion mass spectrometry Repeatability and constancy of

5、 the relative-intensity scale in static secondary-ion mass spectrometry Analyse chimique des surfaces Spectromtrie de masse des ions secondaires Rptabilit et constance de lchelle des intensits relatives en spectromtrie statique de masse des ions secondaires BS ISO 23830:2008ISO 23830:2008(E) PDF dis

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10、member body in the country of the requester. 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 2008 All rights reservedBS ISO 23830:2008ISO 23830:2008(E) ISO 2008 All rights rese

11、rved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Symbols and abbreviations1 3 Outline of method 2 4 Method for confirming the repeatability and constancy of the intensity scale.3 4.1 Obtaining the reference sample.3 4.2 Preparation for mounting the sample3 4.3 Mounting the sample.4 4.4 C

12、hoosing the spectrometer settings for which intensity stability is to be determined .4 4.5 Operating the instrument4 4.6 Measurements of the intensity and its repeatability6 4.7 Calculating the intensity repeatability.7 4.8 Procedure for the regular determination of the constancy of the relative-int

13、ensity scale 9 4.9 Next calibration10 Annex A (informative) Example of suitable operating conditions for static SIMS .11 Bibliography 12 BS ISO 23830:2008ISO 23830:2008(E) iv ISO 2008 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of na

14、tional 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 subject for which a technical committee has been established has the right to be represented on that committee. Intern

15、ational organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the

16、rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by

17、at least 75 % of the member bodies casting a vote. 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 identifying any or all such patent rights. ISO 23830 was prepared by Technical Committee ISO/

18、TC 201, Surface chemical analysis, Subcommittee SC 6, Secondary ion mass spectrometry. BS ISO 23830:2008ISO 23830:2008(E) ISO 2008 All rights reserved vIntroduction Static secondary-ion mass spectrometry (SIMS) is used extensively for the surface analysis of complex materials. Static SIMS is most of

19、ten used for identification of materials at surfaces and for the quantification of mixtures, for example functionalized-surface polymer blends. Quantification is usually achieved through measuring relative peak intensities and by comparing these with appropriate peaks from reference materials. Repea

20、tability is important for these measurements in order to understand if any variations observed are significant. The constancy of relative intensities is important for relating work historically to databases as well as establishing the instrument behaviour. Many static SIMS measurements are for the p

21、urpose of identification of an unknown material through the use of pattern matching with spectral libraries. The extent to which this is meaningful depends on the instrument repeatability and stability. There are two important instrumental contributions to the uncertainty of static SIMS intensity me

22、asurements that are addressed in this International Standard: (i) the repeatability of positive-ion relative-intensity measurements and (ii) the drift of the positive-ion relative intensities with time. With negative ions, the control of the surface potential for insulators is not yet sufficiently g

23、ood for high repeatability. Consequently, negative ions are not included in this International Standard, although it is possible that the concept described will work for negative ions if the surface potential control problem is solved. Repeatability is important for analysing the trends and differen

24、ces between samples that are similar. Poor repeatability can erroneously give the conclusion that the samples are significantly different. The instrumental issues that limit the measurement repeatability include the stability of the ion source, charge stabilization, the settings of the detector, the

25、 sensitivity of the instrument to the sample placement, the data-acquisition parameters and the data-processing procedure. This International Standard describes a simple method for confirming the repeatability and constancy of the relative-intensity scale of the instrument so that the instrument beh

26、aviour is characterized and that any remedial action, such as improving the operating procedure or resetting of the instrument parameters, may be made. This method should, therefore, be conducted at regular intervals and is most useful if the data include a period in which the instrument has been ch

27、ecked to be working correctly by the manufacturer or other appropriate body. This method uses a sample of poly(tetrafluoroethylene), which is abbreviated to PTFE, and is applicable to static SIMS spectrometers with charge stabilization. This method does not address all of the possible defects of ins

28、truments since the required tests would be very time-consuming and need both specialist knowledge and equipment. This method is, however, designed to address the basic common problem of repeatability and of drift of the relative-intensity scales of static SIMS instruments. BS ISO 23830:2008BS ISO 23

29、830:2008INTERNATIONAL STANDARD ISO 23830:2008(E) ISO 2008 All rights reserved 1Surface chemical analysis Secondary-ion mass spectrometry Repeatability and constancy of the relative-intensity scale in static secondary-ion mass spectrometry 1 Scope This International Standard specifies a method for co

30、nfirming the repeatability and constancy of the positive-ion relative-intensity scale of static secondary-ion mass spectrometers, for general analytical purposes. It is only applicable to instruments that incorporate an electron gun for charge neutralization. It is not intended to be a calibration o

31、f the intensity/mass response function. That calibration may be made by the instrument manufacturer or another organization. The present method provides data to confirm the constancy of relative intensities with instrument usage. Guidance is given on some of the instrument settings that may affect t

32、his constancy. 2 Symbols and abbreviations A1average combined peak area for the C3F3and C2F5peaks A2average combined peak area for the C7F13and C8F15peaks A3average combined peak area for the C14F27and C15F29peaks d beam diameter (m) e charge on the electron (C) F pulse repetition rate or frequency

33、(s1) (required for time-of-flight systems only) i index for the ith of the 13 mass peaks Iijmatrix of peak intensities for the ith mass peak and jth spectrum iI average peak intensity over the seven spectra j index for the jth of the seven spectra J total ion fluence (ionsm2) n number of complete ra

34、ster frames Nijmatrix of normalized peak intensities for the ith mass peak and jth spectrum p number of ion pulses delivered per pixel (required for time-of-flight systems only) Pijmatrix of relative peak intensities for the ith mass peak and jth spectrum jP average relative peak intensity over nine

35、 mass peaks of the jth spectrum BS ISO 23830:2008ISO 23830:2008(E) 2 ISO 2008 All rights reservedq time-averaged pulsed ion beam current (A) (required for time-of-flight systems only) Q ion beam current (A) (required for non-pulsed systems and for some time-of-flight systems) r relative-intensity re

36、peatability R length of side of square raster (m) SIMS secondary-ion mass spectrometry T total spectrum acquisition time (s) ToF time of flight u unified atomic mass unit U95(A1/A2) uncertainty in A1/A2U95(A3/A2) uncertainty in A3/A2w pulse width (s) X number of pixels along a line of the raster 3 O

37、utline of method Here, the method is outlined so that the detailed procedure, given in Clause 4, may be understood in context. To evaluate a static SIMS spectrometer using this procedure, obtain a fresh reel of PTFE tape, of the type used for domestic plumbing, in order to measure the intensities of

38、 selected SIMS mass peaks with appropriate instrumental settings. This material is chosen because it is readily available, has low surface contamination and has been well characterized by static SIMS to have the surface uniformity to achieve excellent levels of repeatability. The peaks are chosen to

39、 exhibit no mass interference and so the procedure is relevant to instruments with both high and low mass resolution. The initial steps of procuring the sample and setting up the instrument are described in 4.1 to 4.5 and shown in the flowchart in Figure 1 with the relevant paragraph headings paraph

40、rased. In 4.6, mass spectra are acquired in a sequence repeated seven times. These data give the repeatability standard deviations of the peak intensities. These repeatabilities have contributions from the stabilities of the ion source, the surface charge on the sample, the spectrometer detector and

41、 the electronic supplies, as well as from the sensitivity of the measured peak intensity to the sample position and from the statistical noise in the peak. In the method, conditions are defined to ensure that the statistical noise of the measured intensities is relatively small. The value of the rep

42、eatability standard deviation may depend on the sample-positioning procedure. In 4.6.1, the use of a consistent sample-positioning procedure is required and the final calibration is only valid for samples positioned using this positioning procedure. Generally, for static SIMS, the relative peak inte

43、nsities, rather than the absolute intensities, are most important for material identification. In this method, therefore, the scope is limited to determining the constancy of the relative intensities. These determinations are made in 4.7 and their calculation defined in 4.8, as shown in the flowchar

44、t in Figure 1. In practice, the intensity/mass response function of spectrometers may change significantly with instrument use and especially between different operators of the same instrument. It may therefore be useful for each analyst to conduct this procedure. The interval between repeat assessm

45、ents is given in 4.9. It is imperative that the instrument be operated using a documented procedure to help minimize variations in spectral response. BS ISO 23830:2008ISO 23830:2008(E) ISO 2008 All rights reserved 3Figure 1 Flowchart of the sequence of operations of the method (Subclause numbers are

46、 given with items for cross-referencing with the body of the text.) 4 Method for confirming the repeatability and constancy of the intensity scale 4.1 Obtaining the reference sample For the calibration of static SIMS spectrometers, obtain a new reel of PTFE tape of the type used for domestic plumbin

47、g. Label this reel and keep it with your reference samples for later checks in 4.9. NOTE The PTFE is usually in the form of a reel of tape of length 12 m and width 12 mm and approximately 0,075 mm thick. 4.2 Preparation for mounting the sample Samples shall only be handled with clean metal tweezers

48、held using powderless polyethylene gloves. Vinyl gloves, often used in clean rooms, are coated with a release agent from the moulding process and shall not be used. The release agent is very mobile and quickly contaminates the samples. This leads to poor measurement repeatability and poor-quality da

49、ta. BS ISO 23830:2008ISO 23830:2008(E) 4 ISO 2008 All rights reserved4.3 Mounting the sample Remove and discard the first 20 cm of material from the reel obtained in 4.1 and then cut appropriately sized samples from the subsequent material with clean scissors. As the reel is unwound, a fresh surface of PTFE is exposed and it is this surface that is analysed. Do not clean the sample. Mount samples on the sample holder to produce a flat, even surface using a mechanical clamping or fixing method. Do not use adhesive tape. Ens