ISO 11505:2012
(Main)Surface chemical analysis — General procedures for quantitative compositional depth profiling by glow discharge optical emission spectrometry
Surface chemical analysis — General procedures for quantitative compositional depth profiling by glow discharge optical emission spectrometry
ISO 11505:2013 describes a glow discharge optical emission spectrometric (GD-OES) method for the determination of the thickness, mass per unit area and chemical composition of surface layer films. It is limited to a description of general procedures of quantification of GD-OES and is not applicable directly for the quantification of individual materials having various thicknesses and elements to be determined.
Analyse chimique des surfaces — Modes opératoires généraux pour le profilage en profondeur compositionnel quantitatif par spectrométrie d'émission optique à décharge luminescente
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INTERNATIONAL ISO
STANDARD 11505
First edition
2012-12-15
Surface chemical analysis —
General procedures for quantitative
compositional depth profiling by
glow discharge optical emission
spectrometry
Analyse chimique des surfaces — Modes opératoires généraux pour le
profilage en profondeur compositionnel quantitatif par spectrométrie
d’émission optique à décharge luminescente
Reference number
©
ISO 2012
© ISO 2012
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Published in Switzerland
ii © ISO 2012 – All rights reserved
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Principle . 1
4 Apparatus . 1
4.1 Glow discharge optical emission spectrometer. 1
5 Adjusting the glow discharge spectrometer system settings . 3
5.1 General . 3
5.2 Setting the discharge parameters of a DC source . 4
5.3 Setting the discharge parameters of an RF source . . 6
5.4 Minimum performance requirements . 7
6 Sampling . 9
7 Calibration . 9
7.1 General . 9
7.2 Calibration specimens . 9
7.3 Validation specimens .11
7.4 Determination of the sputtering rate of calibration and validation specimens .11
7.5 Emission intensity measurements of calibration specimens .12
7.6 Calculation of calibration equations .12
7.7 Validation of the calibration .12
7.8 Verification and drift correction .13
8 Analysis of test specimens .14
8.1 Adjusting discharge parameters .14
8.2 Setting of measuring time and data acquisition rate .14
8.3 Quantifying depth profiles of test specimens .14
9 Expression of results .15
9.1 Expression of quantitative depth profile .15
9.2 Determination of total coating mass per unit area .15
9.3 Determination of average mass fractions .16
10 Precision .16
11 Test report .16
Annex A (normative) Calculation of calibration constants and quantitative evaluation of
depth profiles .17
Annex B (informative) Suggested spectral lines for determination of given elements .31
Bibliography .33
Foreword
ISO (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 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 Commission (IEC) on all matters of
electrotechnical standardization.
International Standards are drafted in accordance with the 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 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 11505 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee
SC 8, Glow discharge spectroscopy.
iv © ISO 2012 – All rights reserved
INTERNATIONAL STANDARD ISO 11505:2012(E)
Surface chemical analysis — General procedures for
quantitative compositional depth profiling by glow
discharge optical emission spectrometry
1 Scope
This International Standard describes a glow discharge optical emission spectrometric (GD-OES) method
for the determination of the thickness, mass per unit area and chemical composition of surface layer films.
It is limited to a description of general procedures of quantification of GD-OES and is not applicable directly
for the quantification of individual materials having various thicknesses and elements to be determined.
NOTE Any individual standard for a test material will have to specify a scope of a thickness of the surface
layer as well as analyte elements, and include results of interlaboratory tests for validation of the methods.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 14707, Surface chemical analysis — Glow discharge optical emission spectrometry (GD-OES) —
Introduction to use
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical composition
3 Principle
The analytical method described here involves the following processes:
a) cathodic sputtering of the surface layer in a direct current or radio frequency glow discharge device;
b) excitation of the analyte atoms and ions in the plasma formed in the glow discharge device;
c) spectrometric measurement of the intensities of characteristic spectral emission lines of the analyte
atoms and ions as a function of sputtering time (qualitative depth profile);
d) conversion of the qualitative depth profile in units of intensity versus time to mass fraction versus
depth by means of calibration functions (quantification).
Calibration of the system is achieved by measurements on calibration specimens of known chemical
composition and measured sputtering rate.
4 Apparatus
4.1 Glow discharge optical emission spectrometer
4.1.1 General
The required instrumentation includes an optical emission spectrometer system consisting of a
[10]
Grimm type or similar glow discharge source (direct current or radio frequency powered) and a
simultaneous optical spectrometer as described in ISO 14707, capable of providing suitable spectral
lines for the analyte elements. Sequential optical spectrometers (monochromators) are not suitable,
since several analytical wavelengths must be measured simultaneously at high data acquisition speed.
The inner diameter of the hollow anode of the glow discharge source should be in the range 1 mm to
8 mm. A cooling device for thin specimens, such as a metal block with circulating cooling liquid, is also
recommended, but not strictly necessary for implementation of the method.
Since the principle of determination is based on continuous sputtering of the surface layer, the spectrometer
shall be equipped with a digital readout system for time-resolved measurement of the emission intensities.
A system capable of a data acquisition speed of at least 500 measurements/second per spectral channel
is recommended, but, for a large number of applications, speeds of > 50 measurements/second per
spectral channel are acceptable.
4.1.2 Selection of spectral lines
For each analyte to be determined, there exist a number of spectral lines which can be used. Suitable
lines shall be selected on the basis of several factors, including the spectral range of the spectrometer
used, the analyte mass fraction range, the sensitivity of the spectral lines and any spectral interference
from other elements present in the test specimens. For applications where several of the analytes of
interest are major elements in the specimens, special attention shall be paid to the occurrence of self-
absorption of certain highly sensitive spectral lines (so-called resonance lines). Self-absorption causes
nonlinear calibration curves at high analyte mass fraction levels, and strongly self-absorbed lines should
therefore be avoided for the determination of major elements. Suggestions concerning suitable spectral
lines are given in Annex B. Spectral lines other than those listed may be used, as long as they have
favourable characteristics.
4.1.3 Selection of glow discharge source type
4.1.3.1 Anode size
Most GD-OES instruments on the market are delivered with options to use various anode diameters,
with 2 mm, 4 mm and 8 mm being the most common. Some older instruments have one anode only,
usually 8 mm, while the most commonly used anode in modern instruments is 4 mm. A larger anode
requires larger specimens and higher power during analysis; therefore the specimen is heated to a
greater extent. On the other hand, a larger anode gives rise to a plasma of larger volume that emits more
light, resulting in lower detection limits (i.e. higher analytical sensitivity). Furthermore, a larger anode
helps to mask inhomogeneity within a surface layer. This may or may not be an advantage, depending
on the application. In a large number of applications, the 4 mm anode is a good compromise. However, in
surface analysis applications it is rather common to encounter problems of overheating of the specimens
due to, e.g. surface layers of poor heat conductivity and/or very thin specimens. In such cases, the smaller
2 mm anode is preferable, even if there is some loss of analytic
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