Overview
ISO 18118:2024 - "Surface chemical analysis - Auger electron spectroscopy and X‑ray photoelectron spectroscopy - Guide to the use of experimentally determined relative sensitivity factors for the quantitative analysis of homogeneous materials" - provides guidance on measuring and using experimentally determined relative sensitivity factors (RSFs) for quantitative surface analysis by Auger electron spectroscopy (AES) and X‑ray photoelectron spectroscopy (XPS). The standard applies to homogeneous polycrystalline and amorphous materials and explicitly excludes effects specific to single‑crystal samples.
Key topics and requirements
- Scope and definitions: clear terminology for RSF types - elemental RSF, atomic RSF (ARSF), pure‑element RSF (PERSF) and average matrix RSF (AMRSF) - aligned with ISO 18115‑1 vocabulary.
- Measurement conditions: guidance on instrument settings that affect RSFs, including excitation source, energy resolution, energy step and scan rate, signal intensity, gain/time constant (for analogue AES), and modulation for derivative spectra.
- Data‑analysis procedures: recommended workflows to extract peak intensities and apply RSFs for quantitative composition calculations.
- Spectrometer response function: description of the response/transmission dependence on energy and how it factors into RSF use.
- Composition calculation and uncertainty: formulae and methods for converting measured intensities to atomic concentrations using RSFs, and guidance on evaluating measurement uncertainty (see informative Annex B).
- Normative and informative material: references to ISO 18115‑1 (vocabulary) and ISO 21270 (spectrometer linearity); Annex A contains informative formulae and pointers to parameter databases now recommended over some older formulae.
- Editorial and technical updates: the 2024 third edition moved main equations into the body, consolidated symbols, and updated references to more accurate parameter databases.
Applications and users
ISO 18118:2024 is intended for professionals and organizations performing surface chemical quantification by AES and XPS, including:
- Surface analysts and materials scientists quantifying elemental composition of coatings, thin films, oxides and contamination layers
- Semiconductor and electronics process control laboratories
- Failure analysis and corrosion investigators
- Instrument manufacturers and software developers implementing RSF‑based quantification routines
- Quality assurance teams and accreditation bodies that require documented, reproducible quantification methods
Using ISO 18118 helps ensure consistent, traceable RSF measurement and application, improving comparability of AES/XPS quantitative results across labs and instruments.
Related standards
- ISO 18115‑1 - Surface chemical analysis vocabulary (normative)
- ISO 21270 - XPS/AES spectrometer linearity (normative)
Keywords: ISO 18118:2024, Auger electron spectroscopy, X‑ray photoelectron spectroscopy, relative sensitivity factors, AES, XPS, quantitative surface analysis, homogeneous materials.