Physics and spectroscopy · 1824–1887
Gustav Robert Kirchhoff
Kirchhoff worked on electrical circuits, elasticity and radiation, and his contribution to the spectroscopic partnership was the theoretical half. He showed that a substance absorbs strongly at exactly the wavelengths at which it emits strongly, which explains why the dark lines Fraunhofer had catalogued in the solar spectrum coincide with bright lines from terrestrial flames. That single result converted a catalog of positions into a statement about composition, and made the Sun analysable.
Explore the supporting references at the foot of this article.
Contribution & context
In 1859–1860, with Bunsen, he established analysis as a method and used it to identify sodium and other elements in the solar atmosphere. He did not himself pursue new elements, but the two announced cesium and rubidium jointly on the strength of the method.
NIST — CesiumUSGS — CesiumRSC Periodic Table — CesiumNIST — CesiumRSC Periodic Table — Potassium
Discoveries in context
Elements found by their colors ↗
Once a flame’s light could be spread into sharp lines and matched against a catalog, an element could be detected before anyone had a weighable sample of it.
Sources & further reading
- NIST — Cesium ↗National Institute of Standards and TechnologyReference explanation · Source checked
- USGS — Cesium ↗United States Geological SurveyReference explanation · Source checked
- RSC Periodic Table — Cesium ↗Royal Society of ChemistryReference explanation · Source checked
- NIST — Cesium ↗National Institute of Standards and TechnologyReference explanation · Source checked
- RSC Periodic Table — Potassium ↗Royal Society of ChemistryReference explanation · Source checked
Sources and further reading. What the review labels mean