NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering

Area of Science:

• Materials Science
• Analytical Chemistry
• Physics

Background:

• Accurate intensity calibration is crucial for quantitative analysis in small-angle X-ray scattering (SAXS).
• Existing calibration methods can be instrument-specific and lack universal applicability.
• A need exists for a stable, robust standard reference material for SAXS intensity calibration.

Purpose of the Study:

• To present the certification of NIST Standard Reference Material (SRM) 3600, an absolute intensity calibration standard for SAXS.
• To describe the methodology for achieving and validating the intensity calibration of the SRM.
• To outline the intended use, availability, and universal applicability of the new SAXS standard.

Main Methods:

• Development of SRM 3600 based on glassy carbon, leveraging ultra-small-angle X-ray scattering (USAXS) primary calibration capabilities.
• Intensity calibration achieved and validated within the certified Q range of 0.008–0.25 Å⁻¹.
• Validation of SAXS intensity calibration using small-angle neutron scattering (SANS) techniques.

Main Results:

• Successful certification of SRM 3600 as an absolute intensity calibration standard for SAXS.
• Demonstrated universal applicability of the SRM for SAXS instruments with transmission geometry across diverse X-ray energies/wavelengths.
• Validation of the SRM's SAXS intensity calibration using SANS, with potential for future SANS inclusion.

Conclusions:

• NIST SRM 3600 provides a reliable and universally applicable standard for SAXS absolute intensity calibration.
• The SRM enhances the accuracy and comparability of SAXS data across different instruments and laboratories.
• Future work may extend the SRM's utility to include small-angle neutron scattering calibration.