Triatomic hydrogen

Triatomic hydrogen or H₃ is an unstable molecule composed of three atoms of hydrogen.

The neutral molecule can be formed in a low pressure gas discharge tube.^[1]

It can break up in the following ways:

H_{3}\quad \longrightarrow \quad H_{3}^{+}\ +\ e^{-}

^[2]

H_{3}^{+}\ +\ e^{-}\quad \longrightarrow \quad H_{3}^{*}\quad \longrightarrow \quad H\ +\ H_{2}

H_{3}^{+}\ +\ e^{-}\quad \longrightarrow \quad H_{3}^{*}\quad \longrightarrow \quad H\ +\ H\ +\ H

The molecule can only exist in an excited state. Examples of these states are:^[3] 2sA₁' 3sA₁' 2pA₂" 3dE' 3DE" 3dA₁' 3pE' 3pA₂". The 2p²A₂" state has a lifetime of 700 ns. If the molecule attempts to lose energy and go to the repulsive ground state, it spontaneously breaks up. The lowest energy metastable state, 2sA₁' has an energy -3.777 eV below the H₃⁺ and e^- state but decays in around 1 ps.^[3]

The most stable state is a Trihydrogen cation with an electron delocalized around it.^{[citation needed]}

The H₃⁺ ion is the most prevalent molecular ion in interstellar space. It is believed to have played a crucial role in the cooling of early stars in the history of the Universe through its ability readily to absorb and emit photons.^[4]

One of the first studies was the work of Wendt and Landauer in 1920. They named the substance "Hyzone" in analogy to ozone.^[5]

References

^ Binder, J.L.; Filby, E.A.;Grubb, A.C. (1930). "Triatomic Hydrogen". Nature. 126 (3166): 11–12. doi:10.1038/126011c0.{{cite journal}}: CS1 maint: multiple names: authors list (link)
^ Helm H. et al.: of Bound States to Continuum States in Neutral Triatomic Hydrogen. in: Dissociative Recombination, ed. S. Guberman, Kluwer Academic, Plenum Publishers, USA, 275-288 (2003) ISBN 0-306-47765-3
^ ^a ^b H. Helm, U. Galster, I. Mistrik, U. Müller, and R. Reichle. "Coupling of Bound States to Continuum States in Neutral Triatomic Hydrogen" (PDF). Department of Molecular and Optical Physics, University of Freiburg, Germany. Retrieved 2009-11-25.{{cite web}}: CS1 maint: multiple names: authors list (link)
^ "H₃⁺ --The Molecule that Lit Up the Universe". The Daily Galaxy. April 11, 2012. Retrieved 13 April 2012.
^ Gerald L. Wendt , Robert S. Landauer, J. Am. Chem. Soc., 1920, 42 (5), pp 930–946

External links

C. H. Green: "Rydberg states of Triatomic Hydrogen"
"Triatom Hydrogen". Department of Molecular and Optical Physics, University of Freiburg, Germany. Retrieved 2009-11-25.

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[1] Binder, J.L.; Filby, E.A.;Grubb, A.C. (1930). "Triatomic Hydrogen". Nature. 126 (3166): 11–12. doi:10.1038/126011c0.{{cite journal}}: CS1 maint: multiple names: authors list (link)

[2] Helm H. et al.: of Bound States to Continuum States in Neutral Triatomic Hydrogen. in: Dissociative Recombination, ed. S. Guberman, Kluwer Academic, Plenum Publishers, USA, 275-288 (2003) ISBN 0-306-47765-3

[couple-3] H. Helm, U. Galster, I. Mistrik, U. Müller, and R. Reichle. "Coupling of Bound States to Continuum States in Neutral Triatomic Hydrogen" (PDF). Department of Molecular and Optical Physics, University of Freiburg, Germany. Retrieved 2009-11-25.{{cite web}}: CS1 maint: multiple names: authors list (link)

[4] "H₃⁺ --The Molecule that Lit Up the Universe". The Daily Galaxy. April 11, 2012. Retrieved 13 April 2012.

[5] Gerald L. Wendt , Robert S. Landauer, J. Am. Chem. Soc., 1920, 42 (5), pp 930–946

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