Molecular Abundance Enhancements in the Highly Collimated Bipolar Outflow BHR 71

Garay, Guido; Köhnenkamp, Ive; Bourke, Tyler L.; Rodrı́guez, Luis F.; Lehtinen, K.

doi:10.1086/306534

Cited by 64 publications

(78 citation statements)

References 46 publications

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“…In H 3 O + , no large changes of the rate coefficient have been found upon deuteration by Jensen et al 29 Interestingly, the CRYRING experiment yielded a DR rate coefficient at 300 K which was more than a factor of 2 lower in D 3 …”

Section: Discussionmentioning

confidence: 93%

“…Reaction (5) probably proceeds over small clusters of protonated methanol, which have been found to be preferentially formed in methanol-noble gas mixtures by electron impact ionisation. 25 3 18 OD + . After extraction of the ions from the source at 40 keV, they were mass selected, injected into the ring and accelerated to 2.90 MeV (CH 3 OH 2 + ) and 2.53 MeV (CD 3 OD 2 + ) translational energy.…”

Section: Methodsmentioning

confidence: 99%

“…It has been identified in dark clouds, 2 bipolar outflows, 3 low mass protostars, 4 massive star-forming regions, 5 cometary comae 6 and even in extragalactic sources. 7 Masers of methanol have been described as excellent tracers of star formation.…”

Section: Introductionmentioning

confidence: 99%

“…11 Despite the ample occurrence of methanol and the abundance of information gained by observations of this species, its interstellar formation has so far remained elusive. Although processes on grain surfaces and in grain mantles have been discussed, 12-14 a two step gas phase mechanism involving the radiative association of CH 3 + and H 2 O with subsequent dissociative recombination (DR) of the resulting CH 3 OH 2 + ion has been thought to be responsible for interstellar methanol production CH Radiative association reactions normally have rate coefficients that are too low to successfully compete with other interstellar ion processes. However, it can be argued that in more complicated systems the radiative lifetime of the excited adduct could be on the same scale as its dissociative lifetime.…”

Section: Introductionmentioning

confidence: 99%

“…18,19 However, there are several problems with this reasoning. The interstellar abundance of CH 3 + has never been measured and has therefore to be taken from model predictions, which could differ considerably from the actual densities. Another source of error might be the interstellar abundance of water.…”

Section: Introductionmentioning

confidence: 99%

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Dissociative recombination of protonated methanol

et al. 2006

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The branching ratios of the different reaction pathways and the overall rate coefficients of the dissociative recombination reactions of CH 3 OH 2 + and CD 3 OD 2 + have been measured at the CRYRING storage ring located in Stockholm, Sweden. Analysis of the data yielded the result that formation of methanol or deuterated methanol accounted for only 3 and 6% of the total rate in CH 3 OH 2 + and CD 3 OD 2 + , respectively. Dissociative recombination of both isotopomeres mainly involves fragmentation of the C-O bond, the major process being the three-body break-up forming CH 3 , OH and H (CD 3 , OD and D). The overall cross sections are best fitted by s = 1.2 AE 0.1 Â 10 À15 E À1.15AE0.02 cm 2 and s = 9.6 AE 0.9 Â 10 À16 E À1.20AE0.02 cm 2 for CH 3 OH 2 + and CD 3 OD 2 + , respectively. From these values thermal reaction rate coefficients of k(T) = 8.9 AE 0.9 Â 10 À7 (T/300) À0.59AE0.02 cm 3 s À1 (CH 3 OH 2 + ) and k(T) = 9.1 AE 0.9 Â 10 À7 (T/300) À0.63AE0.02 cm 3 s À1 (CD 3 OD 2 + ) can be calculated. A non-negligible formation of interstellar methanol by the previously proposed mechanism via radiative association of CH 3 + and H 2 O and subsequent dissociative recombination of the resulting CH 3 OH 2 + ion to yield methanol and hydrogen atoms is therefore very unlikely.

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Section: Discussionmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dissociative recombination of protonated methanol

et al. 2006

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When electrons meet molecular ions and what happens next: Dissociative recombination from interstellar molecular clouds to internal combustion engines

Thomas

2008

Mass Spectrometry Reviews

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The interaction of matter with its environment is the driving force behind the evolution of 99% of the observed matter in the universe. The majority of the visible universe exists in a state of weak ionization, the so called fourth state of matter: plasma. Plasmas are ubiquitous, from those occurring naturally; interstellar molecular clouds, cometary comae, circumstellar shells, to those which are anthropic in origin; flames, combustion engines and fusion reactors. The evolution of these plasmas is driven by the interaction of the plasma constituents, the ions, and the electrons. One of the most important subsets of these reactions is electron-molecular ion recombination. This process is significant for two very important reasons. It is an ionization reducing reaction, removing two ionised species and producing neutral products. Furthermore, these products may themselves be reactive radical species which can then further drive the evolution of the plasma. The rate at which the electron reacts with the ion depends on many parameters, for examples the collision energy, the internal energy of the ion, and the structure of the ion itself. Measuring these properties together with the manner in which the system breaks up is therefore critical if the evolution of the environment is to be understood at all. Several techniques have been developed to study just such reactions to obtain the necessary information on the parameters. In this paper the focus will be on one the most recently developed of these, the Ion Storage Ring, together with the detection tools and techniques used to extract the necessary information from the reaction.

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