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Unlike the helium hydride ion, the neutral helium hydride molecule HeH is not stable in the ground state. However, it does exist in an excited state as an excimer (HeH*), and its spectrum was first observed in the mid-1980s. [19] [20] [21] The neutral molecule is the first entry in the Gmelin database. [4]
The helium hydride ion HeH + has been known since 1925. [70] The protonated dihelium ion He 2 H + can be formed when the dihelium cation reacts with dihydrogen: He + 2 + H 2 → He 2 H + + H. This is believed to be a linear molecule. [70] Larger protonated helium cluster ions exist He n H + with n from 3 to 14. He 6 H + and He 13 H + appear to ...
The unusual stability of the helium-4 nucleus is also important cosmologically: it explains the fact that in the first few minutes after the Big Bang, as the "soup" of free protons and neutrons which had initially been created in about 6:1 ratio cooled to the point that nuclear binding was possible, almost all first compound atomic nuclei to ...
A cosmic ray proton at lower energy can also strip an electron off a neutral hydrogen molecule to form a neutral hydrogen atom and the dihydrogen cation, (+ + + +) with a peak cross section at around 8000 eV of 8 × 10 −16 cm 2. [25]
This was tried in operation Upshot–Knothole, [7] where hydrogen was used to reduce the critical mass. The test explosions codenamed Ruth and Ray used in the core uranium hydride. Ruth used the hydrogen isotope protium (1 H) and Ray used the hydrogen isotope deuterium (2 H or 2 D) as neutron moderators. The predicted yield was 1.5 to 3 kt TNT ...
2 He is an intermediate in the first step of the proton–proton chain. The first step of the proton-proton chain is a two-stage process: first, two protons fuse to form a diproton: 1 H + 1 H + 1.25 MeV → 2 He; then the diproton immediately beta-plus decays into deuterium: 2 He → 2 H + e + + ν e + 1.67 MeV; with the overall formula
Argonium (also called the argon hydride cation, the hydridoargon(1+) ion, or protonated argon; chemical formula ArH +) is a cation combining a proton and an argon atom. It can be made in an electric discharge , and was the first noble gas molecular ion to be found in interstellar space.
For example, decay of a tritium-labeled molecule yields an ionized helium atom, which might then break off to leave a cationic molecular fragment. The technique was developed in 1963 by the Italian chemist Fulvio Cacace at the University of Rome. [1] It has allowed the study of a vast number of otherwise inaccessible compounds and reactions.