Alfred Otto Carl Nier

American physicist

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July 23, 2026

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Alfred Otto Carl Nier was an American physicist renowned for his significant contributions to the field of mass spectrometry. He developed a highly sensitive and precise double-focusing mass spectroscope, which was instrumental in accurately measuring the masses and abundances of a vast number of isotopes. Nier's design, alongside that of Mattauch and Herzog, became a popular choice for high-resolution analytical work, particularly in organic chemistry. His work enabled precise mass measurements, advancing the understanding of isotopes and their properties.1

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John R. Dunning
With Alfred Nier and other colleagues, he then showed in 1940 that it was mostly the uranium-235 isotope that was involved in the fission of the uranium nucleus. Dunning went on to direct the research team at Columbia that developed the gaseous-diffusion method of separating uranium-235…
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With Alfred Nier and other colleagues, he then showed in 1940 that it was mostly the uranium-235 isotope that was involved in the fission of the uranium nucleus. Dunning went on to direct the research team at Columbia that developed the gaseous-diffusion method of separating uranium-235…
Read More

dating
Potassium–argon methods
Aldrich and A.O. Nier, the method has evolved into one of the most versatile and widely employed methods available. Potassium is one of the 10 most abundant elements that together make up 99 percent of Earth’s crust and is therefore a major constituent of many rock-forming minerals.…
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Aldrich and A.O. Nier, the method has evolved into one of the most versatile and widely employed methods available. Potassium is one of the 10 most abundant elements that together make up 99 percent of Earth’s crust and is therefore a major constituent of many rock-forming minerals.…
Read More