Editing Irving Langmuir (section)

===Research===
[[Image:Irving Langmuir and Guglielmo Marconi in lab.jpg|thumb|Langmuir ''(center)'' in 1922 in his lab at GE, showing radio pioneer [[Guglielmo Marconi]] ''(right)'' a new 20 kW triode tube]] 
[[Image:General electric pliotron pp schenectady 3.jpg|thumb|right|General Electric Company Pliotron]]

His initial contributions to science came from his study of light bulbs (a continuation of his PhD work). His first major development was the improvement of the [[diffusion pump]], which ultimately led to the invention of the high-vacuum rectifier and amplifier tubes. A year later, he and colleague [[Lewi Tonks]] discovered that the lifetime of a [[tungsten]] filament could be greatly lengthened by filling the bulb with an [[inert gas]], such as [[argon]], the critical factor (overlooked by other researchers) being the need for extreme cleanliness in all stages of the process. 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.<ref>{{harvnb|Coffey|2008|pp=64–70}}</ref>

His assistant in vacuum tube research was his cousin [[William Comings White]].<ref>{{cite journal|doi=10.1109/MPER.2002.989191|title=Irving Langmuir and the origins of electronics|year=2002|last1=Anderson|first1=J. M.|journal=IEEE Power Engineering Review|volume=22|issue=3|pages=38–39 }}</ref>

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 [[Plasma (physics)|plasma]]s, and he was the first to call these ionized gases by that name because they reminded him of [[blood plasma]].<ref>{{cite journal |first=Harold M.|last=Mott-Smith |journal=Nature |volume=233 |issue=5316 |page=219 |year=1971 |title=History of "plasmas" |url=https://www.nature.com/nature/journal/v233/n5316/pdf/233219a0.pdf|bibcode=1971Natur.233..219M |doi=10.1038/233219a0 |pmid=16063290 |s2cid=4259549 |doi-access=free }}</ref><ref>{{cite journal |first=Lewi |last=Tonks |title=The birth of "plasma" |year=1967 |journal=American Journal of Physics |volume=35 |issue=9 |pages=857–858 |doi=10.1119/1.1974266|bibcode=1967AmJPh..35..857T }}</ref><ref>{{cite book|author=Brown, Sanborn C.|chapter=Chapter 1: A Short History of Gaseous Electronics|editor-last1=Hirsh |editor-first1=Merle N. |editor-last2=Oskam |editor-first2=H. J. |title=Gaseous Electronics|volume=1|publisher=Academic Press|date=1978|isbn=978-0-12-349701-7 |chapter-url=https://books.google.com/books?id=C1UmeQ_E0_AC&q=blood&pg=PA1}}</ref> Langmuir and Tonks discovered electron density waves in plasmas that are now known as [[Langmuir wave]]s.<ref>{{cite journal |url=http://www.columbia.edu/~mem4/ap6101/Tonks_Langmuir_PR29.pdf |journal=Physical Review |year=1929 |volume=33 |issue=8 |pages=195–210 |title=Oscillations in ionized gases |first1=Lewi |last1=Tonks |first2=Irving |last2=Langmuir|bibcode=1929PhRv...33..195T |doi=10.1103/PhysRev.33.195 |pmid=16587379 |pmc=1085653 }}</ref>

He introduced the concept of [[Plasma (physics)#Temperature|electron temperature]] and in 1924 invented the diagnostic method for measuring both temperature and [[Plasma (physics)#Degree of ionization|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]].

In 1917, he published a paper on the chemistry of oil films<ref>{{cite journal |title=The Constitution and Fundamental Properties of Solids and Liquids: II. Liquids |doi=10.1021/ja02254a006 |date=September 1917 |last1=Langmuir |first1=Irving |author1-link=Irving Langmuir |journal=Journal of the American Chemical Society |volume=39 |issue=9 |pages=1848–1906|bibcode=1917JAChS..39.1848L |url=https://zenodo.org/record/1429064 }}</ref> 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 [[hydrophilic]] end group (perhaps an [[Alcohol (chemistry)|alcohol]] 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 [[hydrophobic]] 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 [[spectroscopy|spectroscopic]] techniques were available.<ref>{{harvnb|Coffey|2008|pp=128–131}}</ref>