J/ApJ/519/697 Molecular study of HC3NH++e- (Osamura+, 1999)
A molecular orbital study of the HC3NH++e- dissociative recombination
and its role in the production of cyanoacetylene isomers in interstellar clouds
Osamura Y., Fukuzawa K., Terzieva R., Herbst E.
<Astrophys. J. 519, 697 (1999)>
=1999ApJ...519..697O 1999ApJ...519..697O
ADC_Keywords: Atomic physics ; Interstellar medium
Keywords: ISM: molecules - molecular processes
Abstract:
The dissociative recombination reaction between HC3NH+ and
electrons is an important process in the chemistry of interstellar
clouds. Motivated by the evidence that HCN and its metastable isomer
HNC are both formed via the dissociative recombination reaction of
HCNH+, we have examined the potential energy surface for the
dissociation of the transient HC3NH following the recombination
between HC3NH+ and electrons. We find that HC3NH+ gains
151 kcal mol-1 energy by the neutralization; this energy is high
enough to isomerize HC3NH to HCCNCH, as well as to dissociate a
hydrogen atom from either end of the molecule. The present calculation
suggests, therefore, that the metastable linear and near-linear
isomers of HC3N, namely, HNC3, HCCNC, and HCNCC, can be formed via
the dissociative recombination between HC3NH+ and electrons. Two
of these isomers, HNC3 and HCCNC, have already been detected in the
dark cloud TMC-1. The unobserved species HCNCC is energetically the
least stable. Since interstellar HC3N molecules are synthesized
predominantly via neutral-neutral reactions, the HC3NH+ + e-
process serves mainly to produce the metastable isomers of HC3N.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 59 116 Reactions involving HC3N, its isomers, and
their protonated ions
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 8 E8.2 cm3/s Const Constant on the rate coefficient (1)
10- 13 F4.1 --- Sp+Index Power law on the rate coefficient equation
15- 59 A45 --- Reaction The Reaction
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Note (1): Rate coefficients are in the form Const(T/300)Sp+Index, where
Const is in units of cm3.s-1, except for the photodissociation
of HC3N, by internally generated photons, for which Const is
unitless and multiplies the cosmic-ray ionization rate ζ (s-1).
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History:
From ApJ electronic edition
(End) Greg Schwarz [AAS] 28-Apr-2000