Ionization and Dissociation by Electron Impact: Cyanogen, Hydrogen Cyanide, and Cyanogen Chloride and the Dissociation Energy of Cyanogen

1950 ◽  
Vol 18 (10) ◽  
pp. 1347-1351 ◽  
Author(s):  
D. P. Stevenson
Keyword(s):  
Electron Impact ◽  
Dissociation Energy ◽  
Hydrogen Cyanide ◽  
Cyanogen Chloride

scholarly journals THE REACTIONS OF ACTIVE NITROGEN WITH CHLOROMETHANES

1958 ◽  
Vol 36 (9) ◽  
pp. 1223-1226 ◽  
Author(s):  
S. E. Sobering ◽  
C. A. Winkler
Keyword(s):  
Carbon Tetrachloride ◽  
Hydrogen Chloride ◽  
Hydrogen Cyanide ◽  
Active Nitrogen ◽  
Flow Rates ◽  
Product Yields ◽  
Gaseous Products ◽  
Cyanogen Chloride ◽  
Limiting Values ◽  
Reactant Flow

Cyanogen chloride and chlorine were the only gaseous products observed in the reaction of active nitrogen with carbon tetrachloride at 110° and 420 °C. The product yields tended towards limiting values at higher reactant flow rates, and increased with increase of temperature at all flow rates. The reactions of active nitrogen with chloroform and dichloromethane at 260° and 420 °C yielded hydrogen chloride, hydrogen cyanide, and cyanogen, in addition to cyanogen chloride and chlorine. The behavior of the product yields with reactant flow rates and temperature was similar to that of the products from carbon tetrachloride.

The ROSINA Perspective on the CN/HCN Ratio at Comet 67P/Churyumov-Gerasimenko

2020 ◽  
Author(s):  
Nora Hänni ◽  
Kathrin Altwegg ◽  
Martin Rubin
Keyword(s):  
Electron Impact ◽  
Hydrogen Cyanide ◽  
Impact Ionization ◽  
Electron Impact Ionization ◽  
Space Science ◽  
Ammonium Salts ◽  
Ionization Mass ◽  
Direct Production ◽  
Cn Radicals ◽  
Comet 67P

<p>The origin of cyano (CN) radicals in comets presents a long-standing riddle to the science community. Remote observations, e.g. reviewed by Fray et al. [1], show that for some comets the scale lengths, production rates, and spatial distributions of hydrogen cyanide (HCN) and CN using a Haser-based model are not consistent. Consequently, a process additional to photolysis of HCN seems to be required to explain the observed CN densities. Possible scenarios include (1) degradation of CN-producing refractories (e.g. HCN-polymers, tholins, or ammonium salts [2-3]) and (2) photolysis of other gaseous CN-bearing parent species (e.g. HC<sub>3</sub>N or C<sub>2</sub>N<sub>2</sub>).</p><p>The CN/HCN ratio observed in the inner coma of comet 67P/Churyumov-Gerasimenko with the Double Focusing Mass Spectrometer DFMS, part of the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) sensor package [4] onboard ESA’s Rosetta spacecraft, is not compatible with fragmentation of HCN under electron impact ionization. Even though from fragmentation a constant CN/HCN ratio of about 0.15 [5-7] is expected, the observed values range from almost 0.4 at the beginning of the mission (August 2014) to about 0.15 shortly after perihelion passage (August 2015). Towards the end of the mission (September 2016), CN/HCN ratios increase again. This presentation will discuss the data from ROSINA/DFMS in detail and present laboratory-based indications that direct production of CN from sublimating ammonium cyanide (NH<sub>4</sub>CN) occurs, leading to increased CN/HCN ratios. Could this be the process generating a surplus of CN radicals with respect to photolysis of HCN in certain comets?</p><p> </p><p> </p><p>[1] N. Fray et al. The origin oft he CN radical in comets: A review from observations and models Planetary and Space Science 53 (2005) 1243-1262.</p><p>[2] N. Hänni et al. Ammonium Salts as a Source of Small Molecules Observed with High-Resolution Electron-Impact Ionization Mass Spectrometry. J. Phys. Chem. A 123 (2019) 27, 5805-5814.</p><p>[3] K. Altwegg et al. Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae. Nat. Astron. (2019) in print.</p><p>[4] H. Balsiger et al. Rosina - Rosetta Orbiter Spectrometer for Ion and Neutral Analysis. Space Science Reviews 128 (2007) 745-801.</p><p>[5] S.E. Steins in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, Eds. P.J. Linstrom and W.G. Mallard, National Institute of Standards and Technology, (2018).</p><p>[6] P. Kusch et al. The Dissociation of HCN, C<sub>2</sub>H<sub>2</sub>, C<sub>2</sub>N<sub>2</sub>, and C<sub>2</sub>H<sub>4</sub> by Electron Impact. Phys. Rev. 52 (1937) 843-854.</p><p>[7] D. P. Stevenson. Ionization and Dissociation by Electron Impact: Cyanogen, Hydrogen Cyanide, and Cyanogen Chloride and the Dissociation Energy of Cyanogen. J. Chem. Phys. 18 (1950) 1347-1351.</p>

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