?????Silex say -:
We believe that producing enriched silicon-28 to 99.998%is the highest purityever achieved, exceeding the 99.995% purity produced for the InternationalAvogadro Coordination Project*Were the journalists wrong below?https://www.nist.gov/si-redefinitio...on-spheres-and-international-avogadro-project" These individual crystal balls are highly enriched, consisting of
99.9995 percent
silicon-28 with a minimum of the other isotopes found in naturally occurring silicon. This purity simplifies the counting calculations by ensuring that most of the atoms have identical masses, and the sphere’s crystalline structure gives its atoms a predictable pattern of spacing. Devices known as optical interferometers have allowed researchers to measure the sphere’s width to nanometer precision, while the technique of x-ray crystallography provides images of the silicon crystal's structure.
These super-spheres are shared by the teams within the international collaboration.
They each cost about $3.2 million and had to be handcrafted by a master lens maker."
Even the Russians worked out that the highest purity of ZSS contained very little other Isotopes and was to a large extent only Si28!
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