Silicon_Spheres_Definition_Presentation_with_graphics.pptx

This is a slide show prepared for the wrt IPK(Internatinal Prototype of Kilogram)

1. Silicon Spheres: Defining the Kilogram and Mole Using XRCD Method for SI Redefinition

2. Introduction In 2019, the kilogram and mole were redefined based on fundamental constants: - Planck's constant (h) for the kilogram - Avogadro constant (NA) for the mole The XRCD method, using Silicon-28 spheres, enables high precision atom counting.

3. The XRCD Method The X-ray Crystal Density (XRCD) method determines the number of atoms in 28Si spheres. This method links the kilogram and mole to fundamental constants with unprecedented precision.

4. Silicon Spheres and Measurements Silicon-28 spheres are highly enriched and polished to near-perfect shapes for accurate measurements. - Diameter measured via interferometry - Surface layers characterized with XPS, XRF - Core volume determined precisely

5. Realizing the Kilogram and Mole The revised definitions allow precise mass determination: - Planck constant defines kilogram - Avogadro constant defines mole Silicon spheres are now the primary standards for mass and substance amount.

6. Uncertainty and Future While the XRCD method is extremely precise, further improvements are underway to reduce uncertainties in surface characterization and volume measurements.

7. Conclusion Silicon spheres and the XRCD method provide a stable, artifact-free foundation for the kilogram and mole. This innovative approach ensures the long-term accuracy and consistency of mass and amount measurements.

8. Silicon Spheres: Innovation in Measurement