Английская Википедия:Hydrogen ion cluster

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A hydrogen molecular ion cluster or hydrogen cluster ion is a positively charged cluster of hydrogen molecules. The hydrogen molecular ion (Шаблон:Chem) and trihydrogen ion (Шаблон:Chem) are well defined molecular species. However hydrogen also forms singly charged clusters (Шаблон:Chem) with n up to 120.

Experiments

Hydrogen ion clusters can be formed in liquid helium or with lesser cluster size in pure hydrogen. Шаблон:Chem is far more common than higher even numbered clusters. Шаблон:Chem is stable in solid hydrogen. The positive charge is balanced by a solvated electron. It is formed when ionizing radiation impinges on solid hydrogen, and so is formed in radioactive solid tritium. In natural hydrogen treated with radiation, the positive charge transfers to HD molecules, in preference to Шаблон:Chem, with the ultimate most stable arrangement being HD(HD)⁺HD. Шаблон:Chem can migrate through solid hydrogen by linking a hydrogen molecule at one end and losing it at the other: Шаблон:Chem + Шаблон:Chem → Шаблон:Chem + Шаблон:Chem. This migration stops once an HD molecule is added resulting in a lower energy level. HD or Шаблон:Chem is added in preference over Шаблон:Chem.

Clampitt and Gowland found clusters with an odd number of hydrogen atoms Шаблон:Chem and later showed that Шаблон:Chem was relatively stable. Шаблон:Chem formed the core of this cluster with six Шаблон:Chem molecules surrounding it. Hiroka studied the stability of the odd numbered clusters in gas up to Шаблон:Chem. Bae determined that Шаблон:Chem was especially stable amongst the odd numbered clusters.

Kirchner discovered even numbered atomic clusters in gas at lower concentrations than the odd numbered atom clusters. Шаблон:Chem was twenty times less abundant than Шаблон:Chem. Шаблон:Chem, Шаблон:Chem and Шаблон:Chem were detected at lesser amounts than Шаблон:Chem. Kurosaki and Takayanagi showed that Шаблон:Chem is much more stable than other even clusters and showed antiprismatic symmetry of order 4 (Шаблон:Chem molecular symmetry). This turnstile structured molecule was computationally found to be more energetically stable than a ring of five hydrogen atoms around a proton.

Negative hydrogen clusters have not been found to exist. Шаблон:Chem is theoretically unstable, but Шаблон:Chem in theory is bound at 0.003 eV.

Decay

Шаблон:Chem in the free gas state decays by giving off H atoms and Шаблон:Chem molecules. Different energies of decay occur with levels averaging at 0.038 eV and peaking at 0.14 eV.

Formation

Hydrogen molecular ion clusters can be formed through different kinds of ionizing radiation. High energy electrons capable of ionizing the material can perform this task. When hydrogen dissolved in liquid helium is irradiated with electrons their energy must be sufficient to ionize helium to produce significant hydrogen clusters. Irradiation of solid hydrogen by gamma rays or X-rays also produces Шаблон:Chem.

Positive ion clusters are also formed when compressed hydrogen expands though a nozzle.

Kirchner's theory for the formation of even numbered clusters was that neutral Шаблон:Chem molecules reacted with the Шаблон:Chem ion (or other odd clusters) to make Шаблон:Chem.

Properties

Solvation of Шаблон:Chem in solid hydrogen had little effect on its spectrum.

Use

SRI International studied solid ionic hydrogen fuel. They believed that a solid containing Шаблон:Chem and H⁻ ions could be manufactured. If it could be made it would have a higher energy than other rocket fuels with only 2% concentration of ions. However they could not contain the H⁻ in a stable way, but determined that other negative ions would do as well. This theoretical impulse exceeds that of solid and liquid fuel rockets. SRI developed a cluster ion gun that could make positive and negative ion clusters at a current of 500 pA.

Nuclear fusion using ion clusters can impact far more atoms than single ions in one hit. This concept is called cluster ion fusion (CIF). Lithium deuteride (LiD) is a potential starter material for generating the ions.