Trihydrogen cation

Last updated
Trihydrogen cation
Trihydrogen-cation-3D-vdW.png
Names
IUPAC name
Hydrogenonium
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
249
  • InChI=1S/H3/c1-2-3-1/q+1
    Key: RQZCXKHVAUFVMF-UHFFFAOYSA-N
  • [H+]1[H][H]1
Properties
H+3
Molar mass 3.024 g·mol−1
Conjugate base Dihydrogen, H2
Related compounds
Other anions
Hydride
Other cations
Related compounds
 Trihydrogen
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

The trihydrogen cation or protonated molecular hydrogen (IUPAC name: hydrogenonium ion) is a cation (positive ion) with formula H+3, consisting of three hydrogen nuclei (protons) sharing two electrons.

Contents

The trihydrogen cation is one of the most abundant ions in the universe. It is stable in the interstellar medium (ISM) due to the low temperature and low density of interstellar space. The role that H+3 plays in the gas-phase chemistry of the ISM is unparalleled by any other molecular ion.

The trihydrogen cation is the simplest triatomic molecule, because its two electrons are the only valence electrons in the system. It is also the simplest example of a three-center two-electron bond system.

History

H+3 was first discovered by J. J. Thomson in 1911. [1] While using an early form of mass spectrometry to study the resultant species of plasma discharges, he discovered a large abundance of a molecular ion with a mass-to-charge ratio of 3. He stated that the only two possibilities were C4+ or H+3. Since the signal grew stronger in pure hydrogen gas, he correctly assigned the species as H+3.

The formation pathway was discovered by Hogness & Lunn in 1925. [2] They also used an early form of mass spectrometry to study hydrogen discharges. They found that as the pressure of hydrogen increased, the amount of H+3 increased linearly and the amount of H+2 decreased linearly. In addition, there was little H+ at any pressure. These data suggested the proton exchange formation pathway discussed below.

In 1961, Martin et al. first suggested that H+3 may be present in interstellar space given the large amount of hydrogen in interstellar space and its reaction pathway was exothermic (~1.5  eV). [3] This led to the suggestion of Watson and Herbst & Klemperer in 1973 that H+3 is responsible for the formation of many observed molecular ions. [4] [5]

It was not until 1980 that the first spectrum of H+3 was discovered by Takeshi Oka, [6] which was of the ν2 fundamental band (see #Spectroscopy) using a technique called frequency modulation detection. This started the search for extraterrestrial H+3. Emission lines were detected in the late 1980s and early 1990s in the ionospheres of Jupiter, Saturn, and Uranus. [7] [8] [9] In the textbook by Bunker and Jensen [10] Figure 1.1 reproduces part of the ν2 emission band from a region of auroral activity in the upper atmosphere of Jupiter, [11] and its Table 12.3 lists the transition wavenumbers of the lines in the band observed by Oka [6] with their assignments.

In 1996, H+3 was finally detected in the interstellar medium (ISM) by Geballe & Oka in two molecular interstellar clouds in the sightlines GL2136 and W33A. [12] In 1998, H+3 was unexpectedly detected by McCall et al. in a diffuse interstellar cloud in the sightline Cygnus OB2#12. [13] In 2006 Oka announced that H+3 was ubiquitous in interstellar medium, and that the Central Molecular Zone contained a million times the concentration of ISM generally. [14]

Structure

The structure of H+3 H3cation struct.svg
The structure of H+3
The MO diagram of the trihydrogen cation. Trihydrogen-cation-MO-diagram.svg
The MO diagram of the trihydrogen cation.

The three hydrogen atoms in the molecule form an equilateral triangle, with a bond length of 0.90  Å on each side. The bonding among the atoms is a three-center two-electron bond, a delocalized resonance hybrid type of structure. The strength of the bond has been calculated to be around 4.5  eV (104 kcal/mol). [15]

Isotopologues

In theory, the cation has 10 isotopologues, resulting from the replacement of one or more protons by nuclei of the other hydrogen isotopes; namely, deuterium nuclei (deuterons, 2H+) or tritium nuclei (tritons, 3H+). Some of them have been detected in interstellar clouds. [16] They differ in the atomic mass number A and the number of neutrons N:

The deuterium isotopologues have been implicated in the fractionation of deuterium in dense interstellar cloud cores. [17]

Formation

The main pathway for the production of H+3 is by the reaction of H+2 and H2. [18]

H+2 + H2 → H+3 + H

The concentration of H+2 is what limits the rate of this reaction in nature - the only known natural source of it is via ionization of H2 by a cosmic ray in interstellar space:

H2 + cosmic ray → H+2 + e− + cosmic ray

The cosmic ray has so much energy, it is almost unaffected by the relatively small energy transferred to the hydrogen when ionizing an H2 molecule. In interstellar clouds, cosmic rays leave behind a trail of H+2, and therefore H+3. In laboratories, H+3 is produced by the same mechanism in plasma discharge cells, with the discharge potential providing the energy to ionize the H2.

Destruction

The information for this section was also from a paper by Eric Herbst. [18] There are many destruction reactions for H+3. The dominant destruction pathway in dense interstellar clouds is by proton transfer with a neutral collision partner. The most likely candidate for a destructive collision partner is the second most abundant molecule in space, CO.

H+3 + CO → HCO+ + H2

The significant product of this reaction is HCO+, an important molecule for interstellar chemistry. Its strong dipole and high abundance make it easily detectable by radioastronomy. H+3 can also react with atomic oxygen to form OH+ and H2.

H+3 + O → OH+ + H2

OH+ then usually reacts with more H2 to create further hydrogenated molecules.

OH+ + H2 → OH+2 + H
OH+2 + H2 → OH+3 + H

At this point, the reaction between OH+3 and H2 is no longer exothermic in interstellar clouds. The most common destruction pathway for OH+3 is dissociative recombination, yielding four possible sets of products: H2O + H, OH + H2, OH + 2H, and O + H2 + H. While water is a possible product of this reaction, it is not a very efficient product. Different experiments have suggested that water is created anywhere from 5–33% of the time. Water formation on grains is still considered the primary source of water in the interstellar medium.

The most common destruction pathway of H+3 in diffuse interstellar clouds is dissociative recombination. This reaction has multiple products. The major product is dissociation into three hydrogen atoms, which occurs roughly 75% of the time. The minor product is H2 and H, which occurs roughly 25% of the time.

Ortho/Para-H+3

A collision of ortho- H+3 and para- H2. H3+&H2.svg
A collision of ortho-H+3 and para-H2.

The protons of [1H3]+ can be in two different spin configurations, called ortho and para. Ortho-H+3 has all three proton spins parallel, yielding a total nuclear spin of 3/2. Para-H+3 has two proton spins parallel while the other is anti-parallel, yielding a total nuclear spin of 1/2.

The most abundant molecule in dense interstellar clouds is 1H2 which also has ortho and para states, with total nuclear spins 1 and 0, respectively. When a H+3 molecule collides with a H2 molecule, a proton transfer can take place. The transfer still yields a H+3 molecule and a H2 molecule, but can potentially change the total nuclear spin of the two molecules depending on the nuclear spins of the protons. When an ortho-H+3 and a para-H2 collide, the result may be a para-H+3 and an ortho-H2. [18]

Spectroscopy

The spectroscopy of H+3 is challenging. The pure rotational spectrum is exceedingly weak. [19] Ultraviolet light is too energetic and would dissociate the molecule. Rovibronic (infrared) spectroscopy provides the ability to observe H+3. Rovibronic spectroscopy is possible with H+3 because one of the vibrational modes of H+3, the ν2 asymmetric bend mode (see example of ν2) has a weak transition dipole moment. Since Oka's initial spectrum, [6] over 900 absorption lines have been detected in the infrared region. H+3 emission lines have also been found by observing the atmospheres of the Jovian planets. H+3 emission lines are found by observing molecular hydrogen and finding a line that cannot be attributed to molecular hydrogen.

Astronomical detection

H+3 has been detected in two types of the universe environments: jovian planets and interstellar clouds. In jovian planets, it has been detected in the planets' ionospheres, the region where the Sun's high energy radiation ionizes the particles in the planets' atmospheres. Since there is a high level of H2 in these atmospheres, this radiation can produce a significant amount of H+3. Also, with a broadband source like the Sun, there is plenty of radiation to pump the H+3 to higher energy states from which it can relax by spontaneous emission.

Planetary atmospheres

The detection of the first H+3 emission lines was reported in 1989 by Drossart et al., [7] found in the ionosphere of Jupiter. Drossart found a total of 23 H+3 lines with a column density of 1.39×109/cm2. Using these lines, they were able to assign a temperature to the H+3 of around 1,100 K (830 °C), which is comparable to temperatures determined from emission lines of other species like H2. In 1993, H+3 was found in Saturn by Geballe et al. [8] and in Uranus by Trafton et al. [9]

Molecular interstellar clouds

H+3 was not detected in the interstellar medium until 1996, when Geballe & Oka reported the detection of H+3 in two molecular cloud sightlines, GL 2136 and W33A. [12] Both sources had temperatures of H+3 of about 35 K (−238 °C) and column densities of about 1014/cm2. Since then, H+3 has been detected in numerous other molecular cloud sightlines, such as AFGL 2136, [20] Mon R2 IRS 3, [20] GCS 3–2, [21] GC IRS 3, [21] and LkHα 101. [22]

Diffuse interstellar clouds

Unexpectedly, three H+3 lines were detected in 1998 by McCall et al. in the diffuse interstellar cloud sightline of Cyg OB2 No. 12. [13] Before 1998, the density of H2 was thought to be too low to produce a detectable amount of H+3. McCall detected a temperature of ~27 K (−246 °C) and a column density of ~1014/cm2, the same column density as Geballe & Oka. Since then, H+3 has been detected in many other diffuse cloud sightlines, such as GCS 3–2, [21] GC IRS 3, [21] and ζ Persei. [23]

Steady-state model predictions

To approximate the path length of H+3 in these clouds, Oka [24] used the steady-state model to determine the predicted number densities in diffuse and dense clouds. As explained above, both diffuse and dense clouds have the same formation mechanism for H+3, but different dominating destruction mechanisms. In dense clouds, proton transfer with CO is the dominating destruction mechanism. This corresponds to a predicted number density of 10−4 cm−3 in dense clouds.

In diffuse clouds, the dominating destruction mechanism is dissociative recombination. This corresponds to a predicted number density of 10−6/cm3 in diffuse clouds. Therefore, since column densities for diffuse and dense clouds are roughly the same order of magnitude, diffuse clouds must have a path length 100 times greater than that for dense clouds. Therefore, by using H+3 as a probe of these clouds, their relative sizes can be determined.

See also

Related Research Articles

<span class="mw-page-title-main">Hydrogen</span> Chemical element, symbol H and atomic number 1

Hydrogen is a chemical element; it has symbol H and atomic number 1. It is the lightest element and, at standard conditions, is a gas of diatomic molecules with the formula H2, sometimes called dihydrogen, but more commonly called hydrogen gas, molecular hydrogen or simply hydrogen. It is colorless, odorless, tasteless, non-toxic, and highly combustible. Constituting approximately 75% of all normal matter, hydrogen is the most abundant chemical substance in the universe. Stars, including the Sun, primarily consist of hydrogen in a plasma state, while on Earth, hydrogen is found in water, organic compounds, and other molecular forms. The most common isotope of hydrogen consists of one proton, one electron, and no neutrons.

<span class="mw-page-title-main">Molecular cloud</span> Type of interstellar cloud

A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit absorption nebulae, the formation of molecules (most commonly molecular hydrogen, H2), and the formation of H II regions. This is in contrast to other areas of the interstellar medium that contain predominantly ionized gas.

In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the cation [H3O]+, also written as H3O+, the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H+) to the surrounding water molecules (H2O). In fact, acids must be surrounded by more than a single water molecule in order to ionize, yielding aqueous H+ and conjugate base. Three main structures for the aqueous proton have garnered experimental support: the Eigen cation, which is a tetrahydrate, H3O+(H2O)3, the Zundel cation, which is a symmetric dihydrate, H+(H2O)2, and the Stoyanov cation, an expanded Zundel cation, which is a hexahydrate: H+(H2O)2(H2O)4. Spectroscopic evidence from well-defined IR spectra overwhelmingly supports the Stoyanov cation as the predominant form. For this reason, it has been suggested that wherever possible, the symbol H+(aq) should be used instead of the hydronium ion.

<span class="mw-page-title-main">Interstellar medium</span> Matter and radiation in the space between the star systems in a galaxy

In astronomy, the interstellar medium (ISM) is the matter and radiation that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field. Although the density of atoms in the ISM is usually far below that in the best laboratory vacuums, the mean free path between collisions is short compared to typical interstellar lengths, so on these scales the ISM behaves as a gas (more precisely, as a plasma: it is everywhere at least slightly ionized), responding to pressure forces, and not as a collection of non-interacting particles.

<span class="mw-page-title-main">Astrochemistry</span> Study of molecules in the Universe and their reactions

Astrochemistry is the study of the abundance and reactions of molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium. The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites, is also called cosmochemistry, while the study of interstellar atoms and molecules and their interaction with radiation is sometimes called molecular astrophysics. The formation, atomic and chemical composition, evolution and fate of molecular gas clouds is of special interest, because it is from these clouds that solar systems form.

<span class="mw-page-title-main">Hydride</span> Molecule with a hydrogen bound to a more electropositive element or group

In chemistry, a hydride is formally the anion of hydrogen (H−), a hydrogen atom with two electrons. The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are also called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride of nitrogen, etc. For inorganic chemists, hydrides refer to compounds and ions in which hydrogen is covalently attached to a less electronegative element. In such cases, the H centre has nucleophilic character, which contrasts with the protic character of acids. The hydride anion is very rarely observed.

<span class="mw-page-title-main">Hydroxyl radical</span> Neutral form of the hydroxide ion (OH−)

The hydroxyl radical, •HO, is the neutral form of the hydroxide ion (HO–). Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry. Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water. It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments. Hydroxyl radicals are also produced during UV-light dissociation of H2O2 (suggested in 1879) and likely in Fenton chemistry, where trace amounts of reduced transition metals catalyze peroxide-mediated oxidations of organic compounds.

<span class="mw-page-title-main">Ethynyl radical</span> Hydrocarbon compound (•CCH)

The ethynyl radical (systematically named λ3-ethyne and hydridodicarbon(C—C)) is an organic compound with the chemical formula C≡CH (also written [CCH] or C
2H). It is a simple molecule that does not occur naturally on Earth but is abundant in the interstellar medium. It was first observed by electron spin resonance isolated in a solid argon matrix at liquid helium temperatures in 1963 by Cochran and coworkers at the Johns Hopkins Applied Physics Laboratory. It was first observed in the gas phase by Tucker and coworkers in November 1973 toward the Orion Nebula, using the NRAO 11-meter radio telescope. It has since been detected in a large variety of interstellar environments, including dense molecular clouds, bok globules, star forming regions, the shells around carbon-rich evolved stars, and even in other galaxies.

<span class="mw-page-title-main">Helium hydride ion</span> Chemical compound

The helium hydride ion, hydridohelium(1+) ion, or helonium is a cation (positively charged ion) with chemical formula HeH+. It consists of a helium atom bonded to a hydrogen atom, with one electron removed. It can also be viewed as protonated helium. It is the lightest heteronuclear ion, and is believed to be the first compound formed in the Universe after the Big Bang.

Hydrogen isocyanide is a chemical with the molecular formula HNC. It is a minor tautomer of hydrogen cyanide (HCN). Its importance in the field of astrochemistry is linked to its ubiquity in the interstellar medium.

<span class="mw-page-title-main">Diazenylium</span> Chemical compound

Diazenylium is the chemical N2H+, an inorganic cation that was one of the first ions to be observed in interstellar clouds. Since then, it has been observed for in several different types of interstellar environments, observations that have several different scientific uses. It gives astronomers information about the fractional ionization of gas clouds, the chemistry that happens within those clouds, and it is often used as a tracer for molecules that are not as easily detected (such as N2). Its 1–0 rotational transition occurs at 93.174 GHz, a region of the spectrum where Earth's atmosphere is transparent and it has a significant optical depth in both cold and warm clouds so it is relatively easy to observe with ground-based observatories. The results of N2H+ observations can be used not only for determining the chemistry of interstellar clouds, but also for mapping the density and velocity profiles of these clouds.

<span class="mw-page-title-main">Protonated hydrogen cyanide</span> Chemical compound

HCNH+, also known as protonated hydrogen cyanide, is a molecular ion of astrophysical interest. It also exists in the condensed state when formed by superacids.

<span class="mw-page-title-main">Cyclopropenylidene</span> Chemical compound

Cyclopropenylidene, or c-C3H2, is a partially aromatic molecule belonging to a highly reactive class of organic molecules known as carbenes. On Earth, cyclopropenylidene is only seen in the laboratory due to its reactivity. However, cyclopropenylidene is found in significant concentrations in the interstellar medium (ISM) and on Saturn's moon Titan. Its C2v symmetric isomer, propadienylidene (CCCH2) is also found in the ISM, but with abundances about an order of magnitude lower. A third C2 symmetric isomer, propargylene (HCCCH), has not yet been detected in the ISM, most likely due to its low dipole moment.

<span class="mw-page-title-main">Cyano radical</span> Chemical compound

The cyano radical (or cyanido radical) is a radical with molecular formula CN, sometimes written •CN. The cyano radical was one of the first detected molecules in the interstellar medium, in 1938. Its detection and analysis was influential in astrochemistry. The discovery was confirmed with a coudé spectrograph, which was made famous and credible due to this detection. ·CN has been observed in both diffuse clouds and dense clouds. Usually, CN is detected in regions with hydrogen cyanide, hydrogen isocyanide, and HCNH+, since it is involved in the creation and destruction of these species (see also Cyanogen).

Triatomic hydrogen or H3 is an unstable triatomic molecule containing only hydrogen. Since this molecule contains only three atoms of hydrogen it is the simplest triatomic molecule and it is relatively simple to numerically solve the quantum mechanics description of the particles. Being unstable the molecule breaks up in under a millionth of a second. Its fleeting lifetime makes it rare, but it is quite commonly formed and destroyed in the universe thanks to the commonness of the trihydrogen cation. The infrared spectrum of H3 due to vibration and rotation is very similar to that of the ion, H+
3. In the early universe this ability to emit infrared light allowed the primordial hydrogen and helium gas to cool down so as to form stars.

<span class="mw-page-title-main">Imidogen</span> Inorganic radical with the chemical formula NH

Imidogen is an inorganic compound with the chemical formula NH. Like other simple radicals, it is highly reactive and consequently short-lived except as a dilute gas. Its behavior depends on its spin multiplicity.

<span class="mw-page-title-main">Dioxidanylium</span> Ion

Dioxidanylium, which is protonated molecular oxygen, or just protonated oxygen, is an ion with formula HO+
2. It is formed when hydrogen containing substances combust, and exists in the ionosphere, and in plasmas that contain oxygen and hydrogen. Oxidation by O2 in superacids could be by way of the production of protonated molecular oxygen.

Takeshi Oka,, is a Japanese-American spectroscopist and astronomer specializing in the field of galactic astronomy, known as a pioneer of astrochemistry and the co-discoverer of interstellar trihydrogen cation . He is now R.A. Milliken Distinguished Service Emeritus Professor, Departments of Astronomy and Astrophysics, Chemistry; Enrico Fermi Institute; and the College of University of Chicago.

<span class="mw-page-title-main">Argonium</span> Chemical compound

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.

References

  1. ↑ Thomson, J. J. (1913). "Rays of Positive Electricity". Proceedings of the Royal Society A . 89 (607): 1–20. Bibcode:1913RSPSA..89....1T. doi:10.1098/rspa.1913.0057. S2CID   124295244.
  2. ↑ Hogness, T. R.; Lunn, E. G. (1925). "The Ionization of Hydrogen by Electron Impact as Interpreted by Positive Ray Analysis". Physical Review . 26 (1): 44–55. Bibcode:1925PhRv...26...44H. doi:10.1103/PhysRev.26.44.
  3. ↑ Martin, D. W.; McDaniel, E. W.; Meeks, M. L. (1961). "On the Possible Occurrence of H+
    3     in Interstellar Space"    . Astrophysical Journal . 134: 1012. Bibcode:1961ApJ...134.1012M. doi: 10.1086/147232 .
  4. ↑ Watson, W. D. (1973). "The Rate of Formation of Interstellar Molecules by Ion-Molecule Reactions". Astrophysical Journal. 183 (2): L17. Bibcode:1973ApJ...183L..17W. doi:10.1086/181242.
  5. ↑ Herbst, E.; Klemperer, W. (1973). "The Formation and Depletion of Molecules in Dense Interstellar Clouds". Astrophysical Journal. 185: 505. Bibcode:1973ApJ...185..505H. doi: 10.1086/152436 .
  6. 1 2 3 Oka, T. (1980). "Observation of the Infrared Spectrum of H+
    3    ". Physical Review Letters . 45 (7): 531–534. Bibcode:1980PhRvL..45..531O. doi:10.1103/PhysRevLett.45.531.
  7. 1 2 Drossart, P.; et al. (1989). "Detection of H+
    3     on Jupiter"     (PDF). Nature . 340 (6234): 539. Bibcode:1989Natur.340..539D. doi:10.1038/340539a0. hdl: 2027.42/62824 . S2CID   4322920.
  8. 1 2 Geballe, T. R.; et al. (1993). "Detection of H+
    3     Infrared Emission Lines in Saturn"    . Astrophysical Journal. 408 (2): L109. Bibcode:1993ApJ...408L.109G. doi: 10.1086/186843 .
  9. 1 2 Trafton, L. M.; et al. (1993). "Detection of H+
    3     from Uranus". Astrophysical Journal. 405: 761. Bibcode:1993ApJ...405..761T. doi:10.1086/172404.
  10. ↑ Bunker, P. R.; Jensen, P. (2005). Fundamentals of Molecular Symmetry. CRC Press. ISBN   0-7503-0941-5.
  11. ↑ Jean-Pierre Maillard; Pierre Drossart; J. K. G. Watson; S. J. Kim; J. Caldwell (1990). "H + 3 Fundamental Band in Jupiter's Auroral Zones at High Resolution from 2400 to 2900 Inverse Centimeters". Astrophys. J. 363: L37. Bibcode:1990ApJ...363L..37M. doi:10.1086/185859.
  12. 1 2 Geballe, T. R.; Oka, T. (1996). "Detection of H+
    3     in Interstellar Space". Nature. 384 (6607): 334–335. Bibcode:1996Natur.384..334G. doi:10.1038/384334a0. PMID   8934516. S2CID   4370842.
  13. 1 2 McCall, B. J.; et al. (1998). "Detection of H+
    3     in the Diffuse Interstellar Medium Toward Cygnus OB2 No. 12". Science . 279 (5358): 1910–1913. Bibcode:1998Sci...279.1910M. doi:10.1126/science.279.5358.1910. PMID   9506936.
  14. ↑ PNAS, 2006
  15. ↑ McCall, B. J.; et al. (2004). "Dissociative Recombination of Rotationally Cold H+
    3    ". Physical Review A. 70 (5): 052716. Bibcode:2004PhRvA..70e2716M. doi:10.1103/PhysRevA.70.052716.
  16. 1 2 3 4 5 Pagani, L.; Vastel, C.; Hugo, E.; Kokoouline, V.; Greene, C. H.; Bacmann, A.; Bayet, E.; Ceccarelli, C.; Peng, R.; Schlemmer, S. (2009). "Chemical modeling of L183 (L134N): an estimate of the ortho/para H ratio". Astronomy & Astrophysics. 494 (2): 623–636. arXiv: 0810.1861 . doi: 10.1051/0004-6361:200810587 .
  17. 1 2 3 4 5 Roberts, Helen; Herbst, Eric; Millar, T. J. (2003). "Enhanced Deuterium Fractionation in Dense Interstellar Cores Resulting from Multiply Deuterated H3+". Astrophysical Journal Letters. 591 (1): L41–L44. Bibcode:2003ApJ...591L..41R. doi: 10.1086/376962 .
  18. 1 2 3 Herbst, E. (2000). "The Astrochemistry of H+
    3    ". Philosophical Transactions of the Royal Society A . 358 (1774): 2523–2534. Bibcode:2000RSPTA.358.2523H. doi:10.1098/rsta.2000.0665. S2CID   97131120.
  19. ↑ Watson, J.K.G (1971). "Forbidden rotational spectra of polyatomic molecules". Journal of Molecular Spectroscopy. 40 (3): 546–544. Bibcode:1971JMoSp..40..536W. doi:10.1016/0022-2852(71)90255-4.
  20. 1 2 McCall, B. J.; et al. (1999). "Observations of H+
    3     in Dense Molecular Clouds"    . Astrophysical Journal. 522 (1): 338–348. Bibcode:1999ApJ...522..338M. doi: 10.1086/307637 .
  21. 1 2 3 4 Goto, M.; et al. (2002). "Absorption Line Survey of H+
    3     toward the Galactic Center Sources I. GCS 3-2 and GC IRS3"    . Publications of the Astronomical Society of Japan. 54 (6): 951. arXiv: astro-ph/0212159 . doi: 10.1093/pasj/54.6.951 .
  22. ↑ Brittain, S. D.; et al. (2004). "Interstellar H+
    3     Line Absorption toward LkHα 101"    . Astrophysical Journal. 606 (2): 911–916. Bibcode:2004ApJ...606..911B. doi: 10.1086/383024 .
  23. ↑ McCall, B. J.; et al. (2003). "An Enhanced Cosmic-ray Flux towards ζ Persei Inferred from a Laboratory Study of the H+
    3    -e− Recombination Rate". Nature. 422 (6931): 500–2. arXiv: astro-ph/0302106 . Bibcode:2003Natur.422..500M. doi:10.1038/nature01498. PMID   12673244. S2CID   4427350.
  24. ↑ Oka, T. (2006). "Interstellar H3+". PNAS . 103 (33): 12235–12242. Bibcode:2006PNAS..10312235O. doi: 10.1073/pnas.0601242103 . PMC   1567864 . PMID   16894171.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.