BS ISO 14707:2021 pdf download – Surface chemical analysis — Glow discharge optical emission spectrometry (GD-OES) — Introduction to use
This document provides guidelines that are applicable to bulk and depth profiling GD-OES analyses. The guidelines discussed herein are limited to the analysis of rigid solids, and do not cover the analysis of powders, gases or solutions. Combined with specific standard methods which are available now and, in the future, these guidelines are intended to enable the regulation of instruments and the control of measuring conditions.
Although several types of glow discharge optical emission sources have been developed over the years, the Grimm type with a hollow anode accounts for a very large majority of glow discharge optical emission devices currently in use both for dc and rf sources. However, the cathode contact is often located at the back of the sample, in e.g. the Marcus type source, rather than at the front as in the original Grimm design. The guidelines contained herein are equally applicable to both and other source designs and the Grimm type source is used only as an example.
2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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 3497, Metallic coatings — Measurement of coating thickness — X-ray spectrometric methods ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General principles and definitions ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method
ISO 5725-3, Accuracy (trueness and precision) of measurement methods and results — Part 3: Intermediate measures of the precision of a standard measurement method(trueness and precision) of measurement methods and results — Part 3: Intermediate measures of the precision of a standard measurement method
ISO 5725-4, Accuracy (trueness and precision) of measurement methods and results — Part 4: Basic methods for the determination of the trueness of a standard measurement method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 3497, ISO 5725-1, ISO 5725-2, ISO 5725-3 and ISO 5725-4 apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
Glow discharge devices may be operated in either direct current (dc) or radio-frequency (rf) mode. Combinations of these two modes, such as the use of an rf voltage superposed onto a dc voltage, have also been reported. In both the dc and rf power modes, a pulsed discharge is also employed for switching the applied power periodically. The following operations shall be conducted with careful attention to safety (see Annex A):
1) For dc operation, the pertinent electrical parameters are discharge current (1 mA to 200 mA) and voltage (200 V to 2 000 V). In addition to the electrical parameters, other parameters are important for the characteristics of the device. These include the inner diameter of the anode (1 mm to 10 mm), gas type and purity (for example, argon, >99,999 %), gas flow rate or gas pressure introduced (100 ml/min to 500 ml/min, 100 Pa to 1 500 Pa, see note below) and physical characteristics of the sample material (for example, secondary electron emission yield and sputtering yield). The combined effects of all of these factors determine the spectrochemical character of the glow discharge plasma. Generally, it is recommended that the gas flow rate or the gas pressure be varied in real time, in order to achieve constant voltage and current. As an example, typical operating conditions for dc GD-OES bulk analysis of low-alloy steels are 250 ml/min argon flow rate, 600 V to 1 000 V discharge voltage and 20 mA to 60 mA discharge current, for an anode of 4 mm inner diameter. The sputtering rate in this case is typically 100 nm/s varying from 20 nm/s to 160 nm/s for the conditions given in the example.