Neon: properties, production, and applications of the inert gas

In 1894, argon was the first noble gas to be discovered by Lord Rayleigh and William Ramsay. In 1895, Ramsay also isolated helium, previously known only from the solar spectrum, from uranium ores. From the laws of the periodic table, he recognized that between helium and argon there must be another element with an atomic mass of about 20 u.

Therefore, from 1896 onwards, he initially investigated various minerals and meteorites and the gases emitted by them when heated or dissolved. Ramsay and his colleague Morris William Travers were not successful, however, helium and rarely argon were found. Also the investigation of hot gases from Cauterets in France and from Iceland brought no results.

Finally, they began to examine 15 litres of crude argon isolated from liquid air and to separate it by liquefaction and fractional distillation. The first element thus separated and detected on the flame spectrum was krypton, and on 13 June 1898 they finally succeeded in isolating a lighter element from the lower-boiling fraction of the crude argon. This Ramsay and Travers named neon, after the Greek νέος néos, German 'new'. A short time later, they were able to obtain another element, xenon, from the fraction containing krypton.

The first application of the newly discovered gas was the neon lamp developed in 1910 by the Frenchman Georges Claude: neon filled into a glass tube is excited to glow by high voltages.

Neon, especially the isotope ^20Ne, is an important intermediate product in the nucleosynthesis in stars, but is only formed during carbon burning. During helium burning at about 200 - ¹⁰⁶ K, ^{20Ne is} not formed due to the small capture cross section of ^16O for α-particles, only the isotopes ^21Ne and ^22Ne can be formed from the heavier ^18O. If the temperature and density of a star increase significantly after the helium has been consumed, carbon burning occurs, in which two carbon atoms fuse to form an excited magnesium isotope ^{24Mg*. This forms 20Ne} through α-decay.

With a further increase in temperature and pressure, neon burning occurs, in which ^20Ne reacts in α-decay to ^16O or fuses with the resulting helium nuclei to form ^24Mg.

Due to the higher sensitivity of ^20Ne compared to ^16O to gamma radiation, this takes place before the reactions of the lighter oxygen nucleus, which are actually to be expected. Only after the end of the neon burning does the oxygen burning take place, in which heavier elements such as silicon, phosphorus and sulphur are formed from ^16O.