Low-temperature phosphorescence of dicyanoacetylene in rare gas solids

A strong visible ã³Σu⁺ – X̃¹Σg⁺ luminescence was observed upon the UV excitation of cryogenic rare gas (argon, krypton, and xenon) matrices doped with dicyanoacetylene (NC₄N). Spectra and lifetimes of this phosphorescence have been measured. A detailed analysis of resolved vibronic bands is presented

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

Laboratory Experiments of Titan Tholins formed by Photochemistry of Cyanopolyynes

WOS:000342571200006International audienceno abstrac

Laboratory Experiments of Titan Tholins formed by Photochemistry of Cyanopolyynes

WOS:000342571200006International audienceno abstrac

Infrared study of matrix-isolated ethyl cyanide: simulation of the photochemistry in the atmosphere of Titan

International audienceLow-temperature Ar matrix isolation has been carried out to investigate the infrared spectrum of ethyl cyanide (CH 3 CH 2 CN), a molecule present in the atmosphere of Titan. The l 4 120 nm and l 4 230 nm photolysis reactions of ethyl cyanide in an Ar matrix were also performed in order to compare the behaviour of this compound when it is submitted to high and low energetic radiations. These different wavelengths have been used with the aim to reproduce the radiation reaching the various parts of the atmosphere. Several photoproducts have been identified during photolysis such as vinyl cyanide (CH 2 QCHCN), cyanoacetylene (HC 3 N), and ethylene/hydrogen cyanide (C 2 H 4 /HCN), ethylene/hydrogen isocyanide (C 2 H 4 /HNC), acetylene/hydrogen cyanide (C 2 H 2 /HCN), acetylene/hydrogen isocyanide (C 2 H 2 / HNC), and acetylene:methylenimine (C 2 H 2 :HNCH 2) complexes. Ethyl isocyanide (CH 3 CH 2 NC) and a ketenimine form (CH 3 CHQCQNH) have been identified as well. Photoproduct identification and spectral assignments were done using previous studies and density functional theory (DFT) calculations with the B3LYP/cc-pVTZ basis set

Experimental Simulation of Titan's Stratospheric Photochemistry: Benzene (C 6 H 6 ) Ices

International audienceWe performed laboratory experiments to study the photochemical evolution induced by long-UV irradiation of benzene ices in Titan's atmosphere. The aim of this study was to investigate whether photo-processed benzene ices could lead to the formation of aerosols analogs to those observed in Titan's stratosphere. Prior to that, spectroscopic properties of amorphous and crystalline benzene ices were studied as a function of temperature, using infrared spectroscopy. UV photolysis experiments (λ > 230 nm) of benzene ices led to the formation of volatile photo-products, among which fulvene is identified, and of a residue dominated by νCH IR features, demonstrating that pure aromatic-based polymeric structures are not sufficient to explain the composition of Titan's stratospheric haze layer. However, we provide a characterization of long-UV-induced benzene-containing aerosol analogs, which will contribute to Titan's surface organics layer. These data are of prime interest in the context of the future Dragonfly space mission

UV irradiation of benzene in N2 matrix: A relevant study for titan's chemistry

International audienceWe report in this contribution the first photochemical study of benzene trapped in solid nitrogen at low temperature (16 K) and irradiated with a mercury lamp (λ > 230 nm). We identify three benzene isomers (fulvene, Dewar benzene and benzvalene) and two radicals (phenyl and benzyne) as photo-dissociation products, along with acetylene derivatives and substituted benzene. We present for the first time the infrared spectrum of fulvene trapped in benzene ice, which is obtained after nitrogen sublimation. This solid-state characterization could be particularly useful for a better understanding of the photochemical fate of benzene ices recently detected in Titan's atmosphere

Acrylonitrile characterization and high energetic photochemistry at Titan temperatures

WOS:000373249000033International audienceLaboratory infrared spectra of amorphous and crystalline acrylonitrile (C2H3CN) ices were recorded between 4000 and 650 cm(-1). Heating up the acrylonitrile sample to 160 K shows details on the transition between amorphous and crystalline ice at similar to 94 K. This molecule can be used as an indicator of the surface temperature of Titan since it is known also to be similar to 94 K. The desorption energy of acrylonitrile was determined using two methods (IRTF and mass spectrometries) to be around 35 kJ mol(-1). Solid phase acrylonitrile was irradiated with vacuum ultraviolet (VUV) light at low temperatures (20, 70, 95 and 130 K) using a microwave-discharge hydrogen flow lamp. Isoacrylonitrile, cyanoacetylene (HC3N), isocyanoacetylene (HC2NC), acetylene (C2H2) and hydrogen cyanide (HCN) were identified as photoproducts by using FTIR spectroscopy. The branching ratio of each pathway has been calculated for the different temperatures. We have estimated the acrylonitrile, HCN and HC3N v(C) N stretching band strengths to be respectively A = 3.98 x 10(-18), A = 1.38 x 10(-18) and A = 2.92 x 10(-18) cm molecule(-1). (C) 2014 Elsevier Inc. All rights reserved