Irving Langmuir (January 31, 1881 in Brooklyn, New York – August 16, 1957 in Woods Hole, Massachusetts) was an American chemist and physicist. His most noted publication was the famous 1919 article "The Arrangement of Electrons in Atoms and Molecules" in which, building on Gilbert N. Lewis's cubical atom theory and Walther Kossel's chemical bonding theory, he outlined his "concentric theory of atomic structure". Langmuir became embroiled in a priority dispute with Lewis over this work; Langmuir's presentation skills were largely responsible for the popularization of the theory, although the credit for the theory itself belongs mostly to Lewis. While at G.E., from 1909-1950, Langmuir advanced several basic fields of physics and chemistry, invented the gas-filled incandescent lamp, the hydrogen welding technique, and was awarded the 1932 Nobel Prize for Chemistry for his work in surface chemistry. He was the first industrial chemist to become a Nobel laureate. The Langmuir Laboratory for Atmospheric Research near Socorro, New Mexico was named in his honor as was the American Chemical Society journal for Surface Science, called Langmuir.
During his childhood, Langmuir was greatly influenced by his older brother, Arthur Langmuir. Arthur was a research chemist who encouraged Irving to be curious about nature and how things work. Arthur helped Irving set up his first chemistry lab in the corner of his bedroom, and he was content to answer the myriad of questions that Irving would pose. Langmuir's hobbies included mountaineering, skiing, piloting his own plane, and classical music. In addition to his professional interest in the politics of atomic energy, he was deeply concerned about wilderness conservation.
His assistant in vacuum tube research was his cousin William Comings White.
In 1917, he published a paper on the chemistry of oil films that later became the basis for the award of the 1932 Nobel Prize in chemistry. Langmuir theorized that oils consisting of an aliphatic chain with a hydropilic end group (perhpas an alchohol or acid) were oriented as a film one molecule thick upon the surface of water, with the hydrophilic group down in the water and the hydrophilic chains clumped together on the surface. The thickness of the film could be easily determined from the known volume and area of the oil, which allowed investigation of the molecular configuration before spectroscopic techniques were available.
As he continued to study filaments in vacuum and different gas environments, he began to study the emission of charged particles from hot filaments (thermionic emission). He 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.
He 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. The current of a biased probe tip is measured as a function of bias voltage to determine the local plasma temperature and density. 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.
He joined Katharine B. Blodgett to study thin films and surface absorption. They introduced the concept of a monolayer (a layer of material one molecule thick) and the two-dimensional physics which describe such a surface. In 1932 he received the Nobel Prize for Chemistry "for his discoveries and investigations in surface chemistry." In 1938, Langmuir's scientific interests began to turn to atmospheric science and meteorology. One of his first ventures, although tangentially related, was a refutation of the claim of entomologist Charles H. T. Townsend that the deer botfly flew at speeds in excess of 800 miles per hour. Langmuir estimated the fly's true speed at 25 miles per hour.
During World War II, Langmuir worked on improving naval sonar for submarine detection, and later to develop protective smoke screens and methods for deicing aircraft wings. This research led him to theorize that the introduction of dry ice and iodide into a sufficiently moist cloud of low temperature could induce precipitation (cloud seeding); though in frequent practice, particularly in Australia and the People's Republic of China, the efficiency of this technique remains controversial today.
In 1953 Langmuir coined the term "pathological science", describing research conducted with accordance to the scientific method, but tainted by unconscious bias or subjective effects. This is in contrast to pseudoscience, which has no pretense of following the scientific method. In his original speech, he presented ESP and flying saucers as examples of pathological science; since then, the label has been applied to polywater and cold fusion.
After a short illness, he died of a heart attack in 1957. His obituary ran on the front page of the New York Times.