Experimental studies of the dissociative recombination of CD3CDOD+and CH3CH2OH$_{2}^+$Unknown node mtable found in MathML fragment.

Hamberg, Mathias; Zhaunerchyk, Vitali; Vigren, Erik; Kaminska, M.; Kashperka, Iryna; Zhang, M.; Trippel, Sebastian; Österdahl, Fabian; Ugglas, M. af; Thomas, Richard; Källberg, A.; Simonsson, Ansgar; Paál, A.; Semaniak, J.; Larsson, Mats; Geppert, Wolf D.

doi:10.1051/0004-6361/201014774

Cited by 21 publications

(16 citation statements)

References 49 publications

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“…Similarly, the recombination of protonated acetaldehyde produces acetaldehyde in only 9% of electron recombinations. While the rate and products of the protonated formamide recombination are guessed, those of acetaldehyde, from the UMIST database, are measured (Hamberg et al 2010). However, since the two species are destroyed by the same ions, even if the branching ratios of the formamide recombination in the KIDA database are wrong, what matters is the percentage of electron recombinations that give back formamide, which is certainly not unity.…”

Section: Discussionmentioning

confidence: 99%

Seeds of Life in Space (SOLIS)

Codella

Ceccarelli

Caselli

et al. 2017

A&A

109

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Context. Modern versions of the Miller-Urey experiment claim that formamide (NH 2 CHO) could be the starting point for the formation of metabolic and genetic macromolecules. Intriguingly, formamide is indeed observed in regions forming solar-type stars and in external galaxies. Aims. How NH 2 CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods. We used the NOrthern Extended Millimeter Array (NOEMA) interferometer to image NH 2 CHO towards the L1157-B1 blue-shifted shock, a well-known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results. We report the first spatially resolved image (size ∼9 , ∼2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM 5 km s −1 . A column density of N NH 2 CHO = 8 × 10 12 cm −1 and an abundance, with respect to H-nuclei, of 4 × 10 −9 are derived. We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by a gas-phase chemical process and not on grain surfaces as previously suggested. Conclusions. The Seeds of Life in Space (SOLIS) interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas phase around Sun-like protostars.

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Section: Discussionmentioning

confidence: 99%

Seeds of Life in Space (SOLIS)

Codella

Ceccarelli

Caselli

et al. 2017

A&A

109

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“…However, one further destruction mechanism in the gas phase that is not currently included in the chemical network might ameliorate this disagreement. The efficiency of electronic dissociative recombination of protonated molecules in producing the neutral molecule plus a hydrogen atom is generally found only to be on the order of a few percent for the larger highly-saturated complex organic molecules for which experiments have been conducted (e.g., Geppert et al 2006;Hamberg et al 2010). This means that the gas-phase protonation of complex organics typically leads to the destruction of such molecules, thus limiting their lifetimes and fractional abundances.…”

Section: Chemical Modelingmentioning

confidence: 99%

Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

Беллоче

Garrod

Müller

et al. 2019

A&A

158

235

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Context. Urea, NH 2 C(O)NH 2 , is a molecule of great importance in organic chemistry and biology. Two searches for urea in the interstellar medium have been reported in the past, but neither were conclusive. Aims. We want to take advantage of the increased sensitivity and angular resolution provided by the Atacama Large Millimeter/submillimeter Array (ALMA) to search for urea toward the hot molecular cores embedded in the high-mass-star-forming region Sgr B2(N). Methods. We used the new spectral line survey named ReMoCA (Re-exploring Molecular Complexity with ALMA) that was performed toward Sgr B2(N) with ALMA in its observing cycle 4 between 84 GHz and 114 GHz. The spectra were analyzed under the local thermodynamic equilibrium approximation. We constructed a full synthetic spectrum that includes all the molecules identified so far. We used new spectroscopic predictions for urea in its vibrational ground state and first vibrationally excited state to search for this complex organic molecule in the ReMoCA data set. We employed the gas-grain chemical kinetics model MAGICKAL to interpret the astronomical observations. Results. We report the secure detection of urea toward the hot core Sgr B2(N1) at a position called N1S slightly offset from the continuum peak, which avoids obscuration by the dust. The identification of urea relies on nine clearly detected transitions. We derive a column density of 2.7 × 10 16 cm −2 for urea, two orders of magnitude lower than the column density of formamide, and one order of magnitude below that of methyl isocyanate, acetamide, and N-methylformamide. The latter molecule is reliably identified toward N1S with 60 clearly detected lines, confirming an earlier claim of its tentative interstellar detection. We report the first interstellar detections of NH 2 CH 18 O and 15 NH 2 CHO. We also report the nondetection of urea toward the secondary hot core Sgr B2(N2) with an abundance relative to the other four species at least one order of magnitude lower than toward the main hot core. Our chemical model roughly reproduces the relative abundances of formamide, methyl isocyanate, acetamide, and N-methylformamide, but it overproduces urea by at least one order of magnitude. Conclusions. Urea is clearly detected in one of the hot cores. Comparing the full chemical composition of Sgr B2(N1S) and Sgr B2(N2) may help understand why urea is at least one order of magnitude less abundant in the latter source.

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“…While their reaction rates can be accurately determined (Florescu-Mitchell & Mitchell 2006) the products and branching ratios of these reactions are not precisely known (see e.g. Hamberg et al 2010b;Geppert et al 2006).…”

Section: Sensitivity Analysismentioning

confidence: 99%

New Extended Deuterium Fractionation Model: Assessment at Dense Ism Conditions and Sensitivity Analysis

Albertsson

Semenov

Vasyunin

et al. 2013

ApJS

126

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Observations of deuterated species are useful in probing the temperature, ionization level, evolutionary stage, chemistry, and thermal history of astrophysical environments. The analysis of data from ALMA and other new telescopes requires an elaborate model of deuterium fractionation. This paper presents a publicly available chemical network with multi-deuterated species and an extended, up-to-date set of gas-phase and surface reactions. To test this network, we simulate deuterium fractionation in diverse interstellar sources. Two cases of initial abundances are considered: i) atomic except for H 2 and HD, and ii) molecular from a prestellar core. We reproduce the observed D/H ratios of many deuterated molecules, and sort the species according to their sensitivity to temperature gradients and initial abundances. We find that many multiply-deuterated species produced at 10 K retain enhanced D/H ratios at temperatures 100 K. We study how recent updates to reaction rates affect calculated D/H ratios, and perform a detailed sensitivity analysis of the uncertainties of the gas-phase reaction rates in the network. We find that uncertainties are generally lower in dark cloud environments than in warm IRDCs and that uncertainties increase with the size of the molecule and number of D-atoms. A set of the most problematic reactions is presented. We list potentially observable deuterated species predicted to be abundant in low-and high-mass star-formation regions.

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Experimental studies of the dissociative recombination of CD₃CDOD⁺and CH₃CH₂OH$_{2}^+$Unknown node mtable found in MathML fragment.

Cited by 21 publications

References 49 publications

Seeds of Life in Space (SOLIS)

Seeds of Life in Space (SOLIS)

Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea

New Extended Deuterium Fractionation Model: Assessment at Dense Ism Conditions and Sensitivity Analysis

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