- Person
- George de Hevesy
- Lived
- 1885–1966
- Field
- Radiochemistry
- From
- Hungarian
The story
Every element, when struck by energetic radiation, gives off X-rays of characteristic energies, a kind of fingerprint. George de Hevesy, born in Budapest in 1885 into a family of Hungarian-Jewish descent, had seen the power of this at first hand. In Copenhagen in 1922 and 1923, he and Dirk Coster identified the missing element 72, hafnium, from the characteristic lines in its X-ray spectrum.
Supported by the Rockefeller Foundation, de Hevesy had a very productive period in which he developed the X-ray fluorescence analytical method. In this technique a sample is bombarded with high-energy X-rays, and the secondary, or fluorescent, X-rays its atoms give off are measured; their energies identify the elements and their intensities show how much of each is present. The German physicists Glocker and Schreiber also proposed using an X-ray beam in this way in 1928. His Nobel biography records that he introduced the method during his stay in Freiburg, where he was professor of physical chemistry from the mid-1920s.
In the same period he discovered the alpha radiation of samarium, showing that this rare earth element is naturally radioactive. In Freiburg he was also involved in the first clinical use of isotopes, extending his tracer method into medicine.
X-ray fluorescence allowed chemists to work out which elements a material contains, and in what quantities, without destroying it. In 1930 de Hevesy took his expertise to the United States as Baker Lecturer at Cornell University in Ithaca. After the Nazis came to power he left Freiburg, and in 1934 he returned to Copenhagen, where he introduced neutron activation analysis, which his Nobel biography says was to replace the X-ray method. He received the Nobel Prize in Chemistry in 1943 for his work on isotopes as tracers.
X-ray fluorescence lived on. It is now widely used to analyse metals, glass, ceramics and building materials, and in geochemistry, forensic science, archaeology and the study of paintings. Handheld analysers based on it are used in the field and as quality-control tools in industry.
Why it matters
X-ray fluorescence analysis gave scientists a way to determine the elements in a material without destroying the sample.
About George de Hevesy
Hungarian chemist of Jewish origin who invented radioactive tracers, co-discovered hafnium, hid two Nobel medals from the Nazis in acid, and won the 1943 Nobel Prize in Chemistry.
More about George de Hevesy
- George de Hevesy traced lead through a bean plantIn 1923 George de Hevesy published the first use of a radioactive tracer in a living organism, following lead-212 through the roots, stems and leaves of broad beans.
- George de Hevesy co-discovered the element hafniumGuided by Niels Bohr's atomic theory, George de Hevesy and Dirk Coster found the missing element 72 in Copenhagen and named it hafnium, after the city's Latin name.
- George de Hevesy hid colleagues' Nobel medals in acidWhen the Nazis invaded Denmark, chemist George de Hevesy dissolved two colleagues' gold Nobel medals in acid to protect them; after the war the gold was recovered and the medals recast.
- George de Hevesy ran the first radioactive tracer experimentIn early 1913, with Friedrich Paneth at the Vienna Institute for Radium Research, George de Hevesy carried out the first radioactive-tracer experiment.
- George de Hevesy used isotopes to study cancerAfter fleeing to Sweden in 1943, George de Hevesy used labelled atoms to study how X-rays affect nucleic acids in tumours and how iron moves in healthy and cancerous tissue.
- George de Hevesy invented neutron activation analysisIn 1936 George de Hevesy invented neutron activation analysis, identifying tiny traces of elements by bombarding a sample with neutrons and measuring the radioactivity produced.
Sources
- George de Hevesy Wikipedia
- George de Hevesy: Biographical NobelPrize.org
- X-ray fluorescence Wikipedia
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