Overview
ISO 24236:2005 - Surface chemical analysis - Auger electron spectroscopy - Repeatability and constancy of intensity scale specifies a practical method to evaluate how stable and repeatable the intensity scale of Auger electron spectrometers (AES) remains during routine use. It applies to AES instruments that have an ion gun for sputter cleaning and use an electron gun with beam energy of 2 keV or greater. This standard is not a calibration of the intensity/energy response function; rather it provides measurements to assess whether the instrument’s intensity response remains constant over time and use.
Key topics and requirements
- Reference sample: Uses a polycrystalline copper (Cu) foil (≥ 99.8 % purity), typically small foil pieces, prepared and cleaned prior to measurement.
- Cleaning requirement: Samples must be cleaned by ion sputtering (ion gun) to reduce carbon/oxygen contamination before measurements.
- Measurement targets: Intensity measurements of the Cu M VV and Cu L VV Auger peaks in defined instrument modes to probe low and mid kinetic-energy response.
- Repeatability test: A sequence of repeated measurements (standard procedure uses seven repeats) to determine the repeatability standard deviation and measurement uncertainty.
- Instrument settings: The procedure must be repeated for each combination of pass energy, retardation ratio, slits, lens settings, etc., used in routine analysis.
- Evaluation metrics: Calculation of peak heights/intensities, intensity ratios and their uncertainties (95 % confidence) to judge constancy of the intensity scale.
- Routine monitoring: The method supports periodic checks (the standard suggests regular reassessment intervals, e.g., every two months or after substantive instrument changes).
- Limitations: Not exhaustive for all instrument defects; intended to detect drift and repeatability issues rather than replace full manufacturer calibration.
Practical applications and users
Who benefits:
- Surface analysis laboratories performing AES for materials, semiconductor, coatings or thin-film analysis.
- Instrument custodians and QA managers who need a documented procedure for monitoring instrument performance.
- Service engineers and manufacturers as part of validation and post-installation checks.
Practical uses:
- Establishing baseline repeatability after installation or calibration.
- Detecting detector/electronics ageing, beam instability, sample-position sensitivity, or stray magnetic field effects.
- Triggering corrective actions such as recalibration, changed operating procedures, or increased reporting uncertainties.
Related standards
- ISO 17973 and ISO 17974 are referenced for complementary AES energy calibration and related procedures.
- For formal calibration of the intensity/energy response function, follow manufacturer or specialized calibration services.
Keywords: ISO 24236:2005, Auger electron spectroscopy (AES), intensity scale repeatability, intensity constancy, Cu reference foil, ion sputter cleaning, instrument drift, surface chemical analysis.