Overview
ISO/TR 18392:2005 is an informative Technical Report from ISO that provides guidance on determining backgrounds in X-ray photoelectron spectroscopy (XPS) spectra. It summarizes commonly used procedures for removing or modelling background contributions in photoelectron and Auger-electron spectra excited from solid surfaces and surface nanostructures. The report is intended to support accurate, quantitative surface chemical analysis by separating intrinsic spectral features from extrinsic background signals.
Key topics
- Types of background in XPS: contributions from inelastically scattered electrons, secondary-electron cascade, and X‑ray source artefacts (satellites, bremsstrahlung).
- Pre-processing advice: correct for spectrometer response and use digital data handling before background treatment.
- Removal of X‑ray satellites: subtracting scaled satellite-excited photoelectron peaks for non‑monochromated Al/Mg X‑ray sources.
- Background estimation methods:
- Linear background - simple two-point straight-line subtraction (commonly used for polymers and insulators).
- Integral (Shirley) background - iterative algorithm assuming background proportional to higher-energy peak area.
- Tougaard (inelastic-scattering cross-section) - uses models or universal cross-section formulas to predict inelastic-scattering background.
- Partial intensity analysis (PIA) - accounts for both inelastic and elastic scattering by modelling electrons by the number of inelastic collisions.
- Special considerations: intrinsic loss features, inhomogeneous materials, role of elastic scattering, and limitations for specific techniques (e.g., total-reflection XPS or Auger-photoelectron coincidence spectroscopy).
- Comparative guidance on effectiveness and appropriate use cases for each method.
Applications
ISO/TR 18392:2005 supports practical XPS workflows where accurate peak areas, chemical-state identification, and electronic-structure analysis are required:
- Quantitative surface composition and depth profiling of solids and nanostructures
- Chemical-state analysis in materials science, corrosion, catalysis, coatings, polymers, and semiconductors
- Interpretation of Auger-electron and photoelectron spectra where backgrounds obscure intrinsic features
- Development and validation of XPS data-processing software and analysis protocols
Who should use this report
- Surface chemical analysts and spectroscopists working with XPS/AES
- Materials scientists and engineers conducting surface/interface analysis
- Analytical laboratories and instrument/software developers implementing background-correction routines
- Researchers studying nanostructures and thin films requiring precise spectral deconvolution
Related standards
- ISO 18115 (terms and definitions for surface chemical analysis) - referenced for terminology.
- ISO/TR 18392 is an informative Technical Report (state-of-the-art guidance), complementing normative ISO standards for XPS practice.
Keywords: ISO/TR 18392:2005, XPS, X-ray photoelectron spectroscopy, background subtraction, Shirley background, Tougaard background, inelastic scattering, X-ray satellites, surface chemical analysis.
Open preview (PDF)Surface chemical analysis — X-ray photoelectron spectroscopy — Procedures for determining backgrounds
