Hot Hydrogen Atoms: Initiators of Reactions of Interest in Interstellar Chemistry and Evolution

Hong, Kong-Yi; Hong, Jane H.; Becker, Ralph S.

doi:10.1126/science.184.4140.984

Cited by 26 publications

(5 citation statements)

References 7 publications

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“…The energetic environment of a forming protostar would provide a source of dust heating and, because of the estimates for atom binding energies (Tielens & Allamandola 1987), would require that the atoms be contained within the ice matrix, rather than on the surface. Near protostars, atoms in ice matrices may be kinetically ‘hot’ due to production from dissociation of abundant matrix molecules, allowing reactions with activation‐energy barriers to proceed more efficiently, via hot atom reactions (Hong, Hong & Becker 1974; Roessler, Jung & Nebeling 1984), than in cold clouds. Ice radiolysis experiments by Hudson & Moore (1999) do show that methanol and other relevant compounds (CH 3 CHO and C 2 H 5 OH) can be formed by such energetic processing.…”

Section: Posterior Isotopic Labelling Observationsmentioning

confidence: 99%

Observational tests for grain chemistry: posterior isotopic labelling

Charnley¹,

Ehrenfreund²,

Millar³

et al. 2004

Monthly Notices of the Royal Astronomical Society

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We propose a series of detailed observations that should allow current ideas concerning the important catalytic pathways to interstellar molecules on interstellar dust grains to be tested. The atoms and molecules that accrete on cold grains and take part in surface reactions will be selectively fractionated in 13C. Deeply embedded hot cores are surrounded by cold envelopes which still contain molecular ices that reflect the composition of the material evaporated into the hot gas. Recent Infrared Space Observatory observations of carbon dioxide ices towards embedded protostars have allowed the solid [12C/13C] ratio in CO2 to be measured for the first time. We therefore now have a means to test theories of grain chemistry by comparing the isotopic signature of abundant ice molecules with that of species derived from them and which are only detectable in the gas – isotopic labelling a posteriori. If atom addition reactions to solid CO and HCO are the origin of the organic molecules detected in hot molecular cores, these molecules should still possess the same [12C/13C] ratio. The theory that methanol ice is produced by reduction of CO ice can be tested by radio‐astronomical observations of several protostellar sources with known [12CO2/13CO2]ice ratios to see if the observed trend in [12CO2/13CO2]ice is reflected in [12CH3OH/13CH3OH]. We also critically discuss observations designed to elucidate the origin of solid OCS, as well as of many other larger organic molecules.

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Section: Posterior Isotopic Labelling Observationsmentioning

confidence: 99%

Observational tests for grain chemistry: posterior isotopic labelling

Charnley¹,

Ehrenfreund²,

Millar³

et al. 2004

Monthly Notices of the Royal Astronomical Society

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“…Hydrogen atoms are present in most of the materials on earth. The understanding of the chemical bonding of H atoms with other elements became a fundamental problem in chemistry, biology, and physics [ 44 , 45 , 46 , 47 ]. Of particular interest currently are hydride coinage metal clusters that are combinations of metals/hydrogens/electrons, wherein the hydrides are embedded in or ligated to the metal frameworks [ 48 , 49 , 50 ].…”

Section: Resultsmentioning

confidence: 99%

New Insights into Adsorption Properties of the Tubular Au26 from AIMD Simulations and Electronic Interactions

Meng

Liu

2023

Molecules

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Recently, we revealed the electronic nature of the tubular Au26 based on spherical aromaticity. The peculiar structure of the Au26 could be an ideal catalyst model for studying the adsorptions of the Au nanotubes. However, through Google Scholar, we found that no one has reported connections between the structure and reactivity properties of Au26. Here, three kinds of molecules are selected to study the fundamental adsorption behaviors that occur on the surface of Au26. When one CO molecule is adsorbed on the Au26, the σ-hole adsorption structure is quickly identified as belonging to a ground state energy, and it still maintains integrity at a temperature of 500 K, where σ donations and π-back donations take place; however, two CO molecules make the structure of Au26 appear with distortions or collapse. When one H2 is adsorbed on the Au26, the H–H bond length is slightly elongated due to charge transfers to the anti-bonding σ* orbital of H2. The Au26-H2 can maintain integrity within 100 fs at 300 K and the H2 molecule starts moving away from the Au26 after 200 fs. Moreover, the Au26 can act as a Lewis base to stabilize the electron-deficient BH3 molecule, and frontier molecular orbitals overlap between the Au26 and BH3.

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“…Since most of the hydrogen arises from atoms produced in primary events, we assume a sequence based on the primary process 9, demonstrated by Hadley and Volman25 CH3NH2 -CH3NH* + H (9) with a quantum yield of unity. The excited free radical can then decompose in reaction 10 with a probability which CH3NH* -H + CH2=NH* (10) may depend upon the pressure. Reaction 10 is thermodynamically slightly more favorable than the expulsion of molecular hydrogen from CH3NH, but the possibility that reaction 11 occurs cannot be excluded.…”

Section: Discussionmentioning

confidence: 99%

Vacuum-ultraviolet photolysis of methylamine

Gardner¹,

McNesby²

1982

J. Phys. Chem.

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Photolyses of methylamine have been carried out at 184.9,147.0 and 123.6 nm. Quantum yields of hydrogen, hydrocarbons, and nitrogen have been measured. Evidence has also been obtained for the formation of HCN and CN in primary processes at the shorter wavelengths. Photolyses of CD3NH2 in the presence of oxygen and NO provide evidence that H and D atom production dominates at 184.9 nm while H2 and D2 elimination occurs to an important extent at 147.0 and 123.6 nm. The primary process of molecular hydrogen elimination is partly terminal and partly nonterminal.

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Hot Hydrogen Atoms: Initiators of Reactions of Interest in Interstellar Chemistry and Evolution

Cited by 26 publications

References 7 publications

Observational tests for grain chemistry: posterior isotopic labelling

Observational tests for grain chemistry: posterior isotopic labelling

New Insights into Adsorption Properties of the Tubular Au26 from AIMD Simulations and Electronic Interactions

Vacuum-ultraviolet photolysis of methylamine

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