Irving Langmuir was an American physicist and chemist who developed the modern surface chemistry and the theory of absorption catalysis. He discovered monomolecular films with specific molecular orientation at surfaces and promoted understanding of plasmas, heat transfer, and thermionic phenomena. Langmuir also invented a high-vacuum electron tube, gas-filled incandescent lamp. He received the 1932 Nobel Prize in chemistry for his discoveries and investigations in surface chemistry, the first non-academic chemist to receive the Prize. His most noted publication was the famous 1919 article "The Arrangement of Electrons in Atoms and Molecules" in which he outlined his "concentric theory of atomic structure,” building on Gilbert N. Lewis’s cubical atom theory and Walther Kossel’s chemical bonding theory.

Langmuir’s  initial contributions to science came from his study of light bulbs (a continuation of his Ph.D work with doctoral advisor Walther Nernst). His first major development was the improvement of the diffusion pump, which ultimately led to the invention of the high-vacuum tube. A year later, he and colleague Lewi Tonks discovered that the lifetime of a tungsten filament was greatly lengthened by filling the bulb with an inert gas, such as argon. He also discovered that twisting the filament into a tight coil improved its efficiency. These were important developments in the history of the incandescent light bulb. His work in surface chemistry began at this point, when he discovered that molecular hydrogen introduced into a tungsten-filament bulb dissociated into atomic hydrogen and formed a layer one atom thick on the surface of the bulb.

Langmuir was one of the first scientists to work with plasmas and was the first to call these ionized gases by that name, because they reminded him of blood plasma. Langmuir and Tonks discovered electron density waves in plasmas that are now known as Langmuir waves. He also introduced the concept of electron temperature and in 1924 invented the diagnostic method for measuring both temperature and density with an electrostatic probe, now called a Langmuir probe and commonly used in plasma physics. He also discovered atomic hydrogen, which he put to use by inventing the atomic hydrogen welding process; the first plasma weld ever made. Plasma welding has since been developed into gas tungsten arc welding.

Sources

• Cleveland, Cutler (Lead Author); Peter Saundry (Topic Editor). 2008. "Langmuir, Irving." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth September 15, 2006; Last revised August 21, 2008; Retrieved February 23, 2009].
• Wikipedia Contributors, Irving Langmuir, Wikipedia The Free Encyclopedia, Accessed 13 February 2009.