The origin of light emission in the atomic hydrogen—acetylene flame

1964 ◽  
Vol 282 (1389) ◽  
pp. 275-282 ◽  
Keyword(s):  
Gas Phase ◽  
Atomic Hydrogen ◽  
Atomic Oxygen ◽  
Light Emission ◽  
Reactive Intermediates ◽  
Hydrogen Atoms ◽  
Electronically Excited ◽  
Catalytic Recombination ◽  
Oxygen Atoms

Acetylene catalyzes the gas phase recombination of hydrogen atoms, and frequently the reaction is accompanied by a bright flame. It is shown that the light emission is not the result of the catalytic recombination, but is caused by traces of water in the hydrogen. The possible reactive intermediates, OH, HO 2 and atomic oxygen, have been individually generated and added to the mixture of hydrogen atoms and acetylene. Only oxygen atoms are effective in causing luminescence. Hydrogen atoms are not necessary for light emission, but they do alter the spectrum somewhat. Two different mechanisms for the formation of electronically excited C 2 are required. The mechanism for the reaction of atomic oxygen with acetylene is discussed.

scholarly journals Synthesis of methanediol [CH2(OH)2]: The simplest geminal diol

2021 ◽  
Vol 119 (1) ◽  
pp. e2111938119
Author(s):  
Cheng Zhu ◽  
N. Fabian Kleimeier ◽  
Andrew M. Turner ◽  
Santosh K. Singh ◽  
Ryan C. Fortenberry ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Reactive Intermediates ◽  
Hydroxyl Groups ◽  
Unimolecular Decomposition ◽  
Flight Mass Spectrometry ◽  
Criegee Intermediates ◽  
Aldehydes And Ketones ◽  
Electronically Excited ◽  
Geminal Diol

Geminal diols—organic molecules carrying two hydroxyl groups at the same carbon atom—have been recognized as key reactive intermediates by the physical (organic) chemistry and atmospheric science communities as fundamental transients in the aerosol cycle and in the atmospheric ozonolysis reaction sequence. Anticipating short lifetimes and their tendency to fragment to water plus the aldehyde or ketone, free geminal diols represent one of the most elusive classes of organic reactive intermediates. Here, we afford an exceptional glance into the preparation of the previously elusive methanediol [CH2(OH)2] transient—the simplest geminal diol—via energetic processing of low-temperature methanol–oxygen ices. Methanediol was identified in the gas phase upon sublimation via isomer-selective photoionization reflectron time-of-flight mass spectrometry combined with isotopic substitution studies. Electronic structure calculations reveal that methanediol is formed via excited state dynamics through insertion of electronically excited atomic oxygen into a carbon–hydrogen bond of the methyl group of methanol followed by stabilization in the icy matrix. The first preparation and detection of methanediol demonstrates its gas-phase stability as supported by a significant barrier hindering unimolecular decomposition to formaldehyde and water. These findings advance our perception of the fundamental chemistry and chemical bonding of geminal diols and signify their role as an efficient sink of aldehydes and ketones in atmospheric environments eventually coupling the atmospheric chemistry of geminal diols and Criegee intermediates.

Gas phase atomic hydrogen reacting with molecular and atomic oxygen to form water on the Pt(111) surface

1999 ◽  
Vol 419 (2-3) ◽  
pp. 104-113 ◽  
Author(s):  
Adam T Capitano ◽  
Aaron M Gabelnick ◽  
John L Gland
Keyword(s):  
Gas Phase ◽  
Atomic Hydrogen ◽  
Atomic Oxygen

scholarly journals The reaction of atomic hydrogen with hydrazine

1940 ◽  
Vol 175 (961) ◽  
pp. 164-186 ◽  
Keyword(s):  
Hydrogen Atom ◽  
Gas Phase ◽  
Atomic Hydrogen ◽  
Ammonia Molecule ◽  
Para Hydrogen ◽  
Hydrogen Atoms ◽  
Stationary Concentration ◽  
Essential Step ◽  
Photochemical Decomposition ◽  
The Subject

The reason for studying the reaction of hydrogen atoms with hydrazine is that a controversy has arisen in attempting to elucidate the mechanism of the photochemical decomposition of ammonia. It has been generally agreed that the ammonia molecule is decomposed to a hydrogen atom and an amine radical when it absorbs light around 2000° A. Presuming that the atomic hydrogen combines on the walls or in the gas phase it is possible to calculate what its stationary concentration ought to be under any given set of conditions. If, however, the stationary concentration is actually measured by using para-hydrogen as a detector, as was done by Farkas and Harteck (1934), it is found that the measured value is lower than the value calculated from the above assumptions. A number of suggestions, discussed in detail in the following paper, were made to explain this discrepancy, and among the most reasonable was that of Mund and van Tiggelen (1937) who suggested that the hydrazine known to be formed in the system removed such atoms more rapidly than would occur in the ordinary course of events. The result of their suggestion was the invention of elaborate schemes to explain the mechanism of the ammonia photolysis. As a further essential step in the ammonia problem it therefore seemed necessary to measure the efficiency of the reaction between hydrogen atoms and hydrazine. At the same time further information was also desirable about the photochemistry of hydrazine itself. This paper will therefore be concerned with this aspect of the subject. The results will then be discussed in the following paper together with a number of new experiments on ammonia in order that the mechanism of the ammonia reaction may be more fully established.

scholarly journals Atmospheric Loss of Atomic Oxygen during Proton Aurorae on Mars

2021 ◽  
Vol 55 (4) ◽  
pp. 324-334
Author(s):  
V. I. Shematovich
Keyword(s):  
Solar Wind ◽  
Monte Carlo ◽  
Atomic Oxygen ◽  
High Energy ◽  
Neutral Atmosphere ◽  
Hydrogen Atoms ◽  
Oxygen Loss ◽  
Hot Oxygen ◽  
Atmospheric Loss ◽  
Oxygen Atoms

Abstract— For the first time, the calculations of the penetration of protons of the undisturbed solar wind into the daytime atmosphere of Mars due to charge exchange in the extended hydrogen corona (Shematovich et al., 2021) are used allowing us to determine self-consistently the sources of suprathermal oxygen atoms, as well as their kinetics and transport. An additional source of hot oxygen atoms—collisions accompanied by the momentum and energy transfer from the flux of precipitating high-energy hydrogen atoms to atomic oxygen in the upper atmosphere of Mars—was included in the Boltzmann kinetic equation, which was solved with the Monte-Carlo kinetic model. As a result, the population of the hot oxygen corona of Mars has been estimated; and it has been shown that the proton aurorae are accompanied by the atmospheric loss of atomic oxygen, which is evaluated within a range of (3.5–5.8) × 107 cm–2 s–1. It has been shown that the exosphere becomes populated with a substantial amount of suprathermal oxygen atoms with kinetic energies up to the escape energy, 2 eV. The atomic oxygen loss rate caused by a sporadic source in the Martian atmosphere—the precipitation of energetic neutral atoms of hydrogen (H‑ENAs) during proton aurorae at Mars—was estimated by the self-consistent calculations according to a set of the Monte-Carlo kinetic models. These values turned out be comparable to the atomic oxygen loss supported by a regular source—the exothermic photochemical reactions (Groeller et al., 2014; Jakosky et al., 2018). It is currently supposed that the atmospheric loss of Mars due to the impact of the solar wind plasma and, in particular, the fluxes of precipitating high-energy protons and hydrogen atoms during solar flares and coronal mass ejections may play an important role in the loss of the neutral atmosphere on astronomic time scales (Jakosky et al., 2018).

scholarly journals Interaction of Gas-phase Atomic Hydrogen with Chemisorbed Oxygen Atoms on a Silicon Surface

2011 ◽  
Vol 32 (5) ◽  
pp. 1527-1533 ◽  
Author(s):  
Sang-Kwon Lee ◽  
Jong-Baik Ree ◽  
Yoo-Hang Kim ◽  
Hyung-Kyu Shin
Keyword(s):  
Gas Phase ◽  
Atomic Hydrogen ◽  
Silicon Surface ◽  
Chemisorbed Oxygen ◽  
Oxygen Atoms

Gas Phase Atomic Hydrogen-Induced Hydrogenation of Cyclohexene on the Ni(100) Surface

1997 ◽  
Vol 101 (18) ◽  
pp. 3540-3546 ◽  
Author(s):  
Kyung-Ah Son ◽  
John L. Gland
Keyword(s):  
Gas Phase ◽  
Atomic Hydrogen

Chemilumineszenz der SO2-Oxidation / Chemiluminescence of SO2-Oxidation

1978 ◽  
Vol 33 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Joachim Stauff ◽  
Wolfgang Jaeschke
Keyword(s):  
Aqueous Solutions ◽  
Spectral Region ◽  
Time Course ◽  
Light Emission ◽  
Analog Computer ◽  
Reaction Scheme ◽  
So2 Oxidation ◽  
Recombination Product ◽  
Electronically Excited ◽  
Ph Range

Abstract The reactions of diluted aqueous solutions of SO2 resp. HSO3-ions with MnO4-or Ce4+ ions in the pH range 1-4 produce chemiluminescence in the spectral region of 450-600 nm. Measurements of the time course of the light emission and their simulation on an analog computer led to a reaction scheme in which a recombination product of primarily formed HSO3 radicals -of a lifetime of about 1 second -appears as precursor of electronically excited SO2 molecules. The participation of singlet oxygen can be excluded because at least the reaction with Ce4+ ions proceeds also in the absence of oxygen.

ChemInform Abstract: The Reaction of Thiolane with Hydrogen Atoms in Gas Phase.

1977 ◽  
Vol 8 (31) ◽  
pp. no-no
Author(s):  
O. HORIE ◽  
K. KAWAMATA ◽  
K. ONUKI ◽  
A. AMANO
Keyword(s):  
Gas Phase ◽  
Hydrogen Atoms
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