ISO 23124:2024
Surface chemical analysis — Measurement of lateral and axial resolutions of a Raman microscope

Standard No.

ISO 23124:2024

Release Date

2024

Published By

International Organization for Standardization (ISO)  IX  /  ISO

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ISO 23124:2024

Introduction

Analysis of the core content of the standard

ISO 23124:2024 has established for the first time a standardized measurement framework for the spatial resolution of Raman microscopy, with key specifications:

• Lateral resolution: measured using the narrow line method of linear samples (such as carbon nanotubes)
• Axial resolution: measured by vertical scanning of suspended ultra-thin materials (such as graphene)

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Technological evolution and standard background

Traditional Raman microscopy resolution assessment has two major pain points:

Problem type	Before standardization	ISO 23124 solution
Measurement method	Manufacturer-defined (straight edge method/grating method, etc.)	Uniformly adopt narrow line method
Sample specification	No clear size requirement	Sample size must be <1/4 of expected resolution
Data comparability	Incomplete parameter recording	Mandatory recording of 12 key parameters

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Details of key measurement requirements

1. Sample preparation specifications

Lateral measurement sample:
CNT diameter should be <1/4 of expected resolution (55nm CNT is used to measure 305nm resolution in the example)

Axial measurement sample:
The thickness of suspended graphene needs to be verified (the single-layer structure is confirmed by the 2D/G peak intensity ratio)

2. Instrument parameter control

• Numerical aperture (NA): directly affects the focused spot size (the standard example uses a NA=0.9 objective lens)
• Confocal aperture size: a typical configuration of a 100μm aperture with a 165mm tube lens
• Laser power density: 6.0×10⁵ W/cm² for lateral measurement, 8.0×10⁴ W/cm² for axial measurement

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Implementation suggestions

1. Calibration verification: Before measurement, the accuracy of the XY stage must be verified with a standard sample
2. Data processing: At least 5 measurements are taken to get the average value, and the signal-to-noise ratio (SNR)>5
3. Parameter recording: 12 items of data such as objective lens specifications, laser wavelength, and grating parameters must be included

Typical measurement case shows:
Under 532nm laser, the 100× objective lens measured a lateral resolution of 305±15.8nm and an axial resolution of 983.8±20.5nm

ISO 23124:2024 history

• 2024 ISO 23124:2024 Surface chemical analysis — Measurement of lateral and axial resolutions of a Raman microscope

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