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We investigate the relative efficiencies of low-temperature chemical reactions in the Interstellar medium (ISM) with H$^-$ anion reacting in the gas phase with cyanopolyyne neutral molecules, leading to the formation of anionic C$_x$N$^-$…

化学物理 · 物理学 2018-07-31 F. A. Gianturco , M. Satta , E. Yurtsever , R. Wester

The final step of the water formation network on interstellar grain surfaces starting from the H + O$_2$ route is the reaction between H and H$_2$O$_2$. This reaction is known to have a high activation energy and therefore at low…

化学物理 · 物理学 2016-12-01 Thanja Lamberts , Pradipta Kumar Samanta , Andreas Köhn , Johannes Kästner

A continuous supersonic flow reactor has been used to measure rate constants for the C + NH3 reaction over the temperature range 50 to 296 K. C atoms were created by the pulsed laser photolysis of CBr4. The kinetics of the title reaction…

The hydrogen abstraction reaction between H and H$_2$S, yielding HS and H$_2$ as products, has been studied within the framework of interstellar surface chemistry. High-temperature rate constants up to 2000 K are calculated in the gas phase…

星系天体物理 · 物理学 2017-12-07 Thanja Lamberts , Johannes Kästner

The product formation channels of ground state carbon atoms, C(3P), reacting with ammonia, NH3, have been investigated using two complementary experiments and electronic structure calculations. Reaction products are detected in a gas flow…

HCN is a molecule central to interstellar chemistry, since it is the simplest molecule containing a carbon-nitrogen bond and its solid state chemistry is rich. The aim of this work was to study the NH3 + HCN -> NH4+CN- thermal reaction in…

地球与行星天体物理 · 物理学 2015-06-11 J. A. Noble , P. Theule , F. Borget , G. Danger , M. Chomat , F. Duvernay , F. Mispelaer , T. Chiavassa

Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N2, with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear…

$Aims$: We revisit with new augmented accuracy the theoretical dynamics of basic isotope exchange reactions involved in the $^{12}$C/$^{13}$C, $^{16}$O/$^{18}$O, and $^{14}$N/$^{15}$N balance because these reactions have already been…

星系天体物理 · 物理学 2015-06-19 Mirjana Mladenović , Evelyne Roueff

Solid state astrochemical reaction pathways have the potential to link the formation of small nitrogen-bearing species, like NH3 and HNCO, and prebiotic molecules, specifically amino acids. To date, the chemical origin of such small…

星系天体物理 · 物理学 2017-05-26 Gleb Fedoseev , Sergio Ioppolo , Dongfeng Zhao , Thanja Lamberts , Harold Linnartz

OH radicals play a key role as an intermediate in the water formation chemistry of the interstellar medium. For example the reaction of OH radicals with H$_2$ molecules is among the final steps in the astrochemical reaction network starting…

星系天体物理 · 物理学 2017-08-21 Jan Meisner , Thanja Lamberts , Johannes Kästner

In the coldest (10--20 K) regions of the interstellar medium, the icy surfaces of interstellar grains serve as solid-state supports for chemical reactions. Among their plausible roles, that of third body is advocated, in which the reaction…

Based on recent $Herschel$ results, the ortho-to-para ratio (OPR) of NH$_2$ has been measured towards the following high-mass star-forming regions: W31C (G10.6-0.4), W49N (G43.2-0.1), W51 (G49.5-0.4), and G34.3+0.1. The OPR at thermal…

星系天体物理 · 物理学 2016-11-30 Romane Le Gal , Eric Herbst , Changjian Xie , Anyang Li , Hua Guo

Context. In dffuse interstellar clouds the excitation temperature derived from the lowest levels of H$^+_3$ is systematically lower than that derived from H2. The differences may be attributed to the lack of state-specific formation and…

The formation of methanol (CH3OH) on icy grain mantles during the star formation cycle is mainly associated with the CO freeze-out stage. Yet there are reasons to believe that CH3OH also can form at an earlier period of interstellar ice…

星系天体物理 · 物理学 2018-05-02 D. Qasim , K. -J. Chuang , G. Fedoseev , S. Ioppolo , A. C. A. Boogert , H. Linnartz

The reaction N(4S) + NO -> O(3P) + N2 plays a pivotal role in the conversion of atomic to molecular nitrogen in dense interstellar clouds and in the atmosphere. Here we report a joint experimental and computational investigation of the N +…

星系天体物理 · 物理学 2023-05-10 Kevin M. Hickson , Juan Carlos San Vicente Veliz , Debasish Koner , Markus Meuwly

The formation of interstellar water has been commonly accepted to occur on the surfaces of icy dust grains in dark molecular clouds at low temperatures (10-20 K), involving hydrogenation reactions of oxygen allotropes. As a result of the…

星系天体物理 · 物理学 2014-10-22 Thanja Lamberts , Herma Cuppen , Gleb Fedoseev , Sergio Ioppolo , Ko-Ju Chuang , Harold Linnartz

Our current understanding of interstellar carbon fractionation hinges on the interpretation of astrochemical kinetic models. Yet, the various reactions included carry large uncertainties in their (estimated) rate coefficients, notably those…

星系天体物理 · 物理学 2021-03-24 C. M. R. Rocha , H. Linnartz

The ion-molecule reactions $\text{D}_2^++\text{NH}_3$ and $\text{D}_2^++\text{ND}_3$ are studied at low collision energies ($E_{\text{coll}}$ from zero to $\sim k_\textrm{B}\cdot 50\,\text{K}$), with the $\text{D}_2^+$ ions in the ground…

化学物理 · 物理学 2024-03-05 Raphaël Hahn , David Schlander , Valentina Zhelyazkova , Frédéric Merkt

The first experimental study of the low-temperature kinetics of the gas-phase reaction of NH2 with formaldehyde (CH2O) has been performed. This reaction has previously been suggested as a source of formamide (NH2CHO) in interstellar…

星系天体物理 · 物理学 2022-10-05 Kevin M. Douglas , Daniel Lucas , Catherine Walsh , Niclas A. West , Mark A. Blitz , Dwayne E. Heard

Interstellar complex organic molecules (COMs) are commonly observed during star formation, and are proposed to form through radical chemistry in icy grain mantles. Reactions between ions and neutral molecules in ices may provide an…

天体物理仪器与方法 · 物理学 2016-10-05 Jennifer B. Bergner , Karin I. Oberg , Mahesh Rajappan , Edith C. Fayolle
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