Overview
ISO 11505:2012 - titled Surface chemical analysis - General procedures for quantitative compositional depth profiling by glow discharge optical emission spectrometry (GD-OES) - defines general, standardized procedures for quantitative depth profiling of surface films using GD-OES. The standard describes how to determine thickness, mass per unit area, and chemical composition of surface layers by converting time‑resolved emission intensities (intensity vs. sputtering time) into mass fraction vs. depth using calibrated emission yields. It is a general quantification procedure and is not intended as a direct, validated method for every individual material/thickness/analyte combination.
Key topics and technical requirements
- Principle: Continuous cathodic sputtering (DC or RF) with plasma excitation and simultaneous spectrometric detection to produce depth profiles; calibration converts intensity–time profiles to quantitative depth.
- Apparatus: Grimm‑type or similar GD source coupled to a simultaneous optical spectrometer (sequential monochromators are not suitable). Hollow anode inner diameters typically range 1–8 mm; 2 mm, 4 mm and 8 mm are common.
- Power supplies: Both DC and RF operation are covered. RF can sputter insulating specimens (polymers, oxides); DC is simpler to measure/control.
- Instrument settings: Guidance on setting discharge parameters, pressure control, and mode of operation; note that emission yield varies with current, voltage and pressure.
- Data acquisition: Time‑resolved digital readout required. Recommended speed: ≥500 measurements/s per spectral channel (≥50/s acceptable for many applications).
- Calibration & validation: Procedures for calibration specimens, validation specimens, sputtering rate determination, emission intensity measurement, calibration equation calculation, validation, drift correction and verification.
- Spectral line selection: Advice on choosing lines to avoid self‑absorption and spectral interferences (Annex B lists suggested lines).
- Annexes: Annex A (calculation of calibration constants and quantitative evaluation) and Annex B (suggested spectral lines).
Practical applications
- Quantitative compositional depth profiling of metallic and coated surfaces, thin films, and layered materials.
- Determination of coating thickness, total coating mass per unit area, and depth distribution of elements in surface layers.
- Useful in quality control, failure analysis, coating development, surface engineering and R&D where depth‑resolved chemical composition is required.
Who should use ISO 11505:2012
- Surface analytical laboratories applying GD‑OES for quantitative depth profiling.
- Instrument manufacturers implementing quantification software and recommended operating modes.
- Quality managers and materials engineers needing standardized procedures for comparative measurements.
- Researchers developing validated, material-specific ISO methods (note: individual methods must specify analyte scope and validate via interlaboratory tests).
Related standards
- ISO 14707 - Introduction to use of GD‑OES (referenced normatively).
- ISO 14284 - Sampling and preparation for chemical composition of steel and iron (referenced).
Keywords: ISO 11505:2012, GD‑OES, glow discharge optical emission spectrometry, depth profiling, surface chemical analysis, calibration, sputtering rate, spectral lines, DC, RF.
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