Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions

Studies of Dense Cores with ALMA

Dense cores are the simplest star-forming sites that we know, but despite their simplicity, they still hold a number of mysteries that limit our understanding of how solar-type stars form. ALMA promises to revolutionize our knowledge of every stage in the life of a core, from the pre-stellar phase to the final disruption by the newly born star. This contribution presents a brief review of the evolution of dense cores and illustrates particular questions that will greatly benefit from the increase in resolution and sensitivity expected from ALMAComment: 6 pages, 2 figures, to appear in Astrophysics and Space Science, special issue of "Science with ALMA: a new era for Astrophysics" conference, ed. Dr. Bachille

Science goals and new mission concepts for future exploration of Titan's atmosphere geology and habitability: Titan POlar Scout/orbitEr and In situ lake lander and DrONe explorer (POSEIDON)

In response to ESA’s “Voyage 2050” announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn’s largest moon Titan. Titan, a “world with two oceans”, is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan’s remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a “heavy” drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan’s northern latitudes with an orbiter and in situ element(s) would be highly complementary in terms of timing (with possible mission timing overlap), locations, and science goals with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan’s equatorial regions, in the mid-2030s

High-resolution ZEKE and REMPI spectroscopy of aromatic molecules with intra- and intermolecular van der Waals bonds

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN031091 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Introduction to the Special Issue - Habitability in the Universe: from the Early Earth to Exoplanets

International audience

One electron reduction and oxidation of 2-, 3- and 4-chlorobenzonitrile in aqueous solution: A pulse radiolysis study

Solvated electrons (e(aq)(-)) react with very high rates (k > 10(10) dm(3) mol(-1) s(-1)) with 2-, 3- and 4-monochlorbenzonitriles (2-, 3- and 4-C1BN) to yield the corresponding radical anions. The anions decay in neutral solution under dechlorination by a first-order reaction, where the k(1)-values of 2- and 4-C1BN species are about three orders of magnitude higher than that of 3-C1BN. At low pHs, the 3-CIBN.- transient protonates k = 2.6 x 10(10) dm(3) mol(-1) s(-1) and the resulting species disappears by a second-order process (2k = 2 x 10(9) dm(3) mol(-1) s(-1)). The spectrum of the protonated 3-C1BN(.-) transient strongly differs from that of the H-adduct. Hence, the protonation of the radical anions seems to occur at the cyano group. The H-atoms form the respective adducts with rates from 2.2 to 3.4 x 10(9) dm(3) mol(-1) s(-1), which disappear by a second-order process with rate constants of 3.6-6.1 x 10(8) dm(3) mol(-1) s(-1). The OH-attack leads to the formation of the corresponding adducts (k = 1.3-1.5 x 10(9) dm(3) mol(-1) s(-1)) which decay by a second-order reaction (2k = 6.1-7.4 x 10(8) dm(3) mol(-1) s(-1)). The absorption spectra observed by the attack of e(aq)(-) H- and OH-radicals are presented. Some probable reaction steps are also given. (C) 2000 Elsevier Science Ltd. All rights reserved

Laboratory gas-phase vibrational spectra of [C3H3]+ isomers and isotopologues by IRPD spectroscopy

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