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8 pags., 9 figs., 4 tabs. ; Urea is a molecule of great interest in chemistry and biology. In particular, it is considered a key building block in prebiotic chemistry on Earth. The hypothesis of its possible exogenous origin has been reinforced after the recent detection of this molecule in the interstellar medium, where it is believed to form in the ice mantles of dust grains. In this work the infrared spectra of urea ices and urea:HO ice mixtures have been studied both experimentally and theoretically. Urea ices were generated by vapour deposition at temperatures between 10 K and 270 K. It was found that an amorphous phase is formed at temperatures below 200 K. A theoretical modelling of crystalline urea and of a tentative amorphous urea solid phase, as well as of amorphous urea:HO ice mixtures, has been performed. The corresponding infrared spectra were simulated with density functional theory. The main spectral features observed in the various solid samples are interpreted with the help of the theoretical results. Infrared band strengths are also provided for amorphous and crystalline urea. The infrared spectroscopic information given in this work is expected to be useful for the detection and quantification of urea in astrophysical ices. ; This work was funded by the Ministerio de Economia y Competitividad (MINECO) and the Ministerio de Ciencia e Innovacion (MCI) of Spain under grants FIS2016-77726-C3-1-P and PID2020-113084GB-I00, respectively, and by the European Union under grant ERC-2013-Syg-210656-NANOCOSMOS. The computation time provided by the Centro Tecnico de Informatica, cluster Trueno from CSIC and Centro de Supercomputacio´n de Galicia CESGA is deeply acknowledged.

The stereodynamics of the Ar + NO (J = 0) rotational inelastic excitation has been investigated at 66 meV by means of quasiclassical trajectories on a recent ab initio potential energy surface. A marked correlation between the preferred sense of rotation of NO and the scattering plane is obtained for the highest rotational levels accessible, which are excited in strong repulsive collisions. This result is in qualitative agreement with recent quantum mechanical calculations and experimental measurements. For the lower rotational levels, where the interactions are not so repulsive, the preferred sense of rotation is found to oscillate with scattering angle, but the intensity of the oscillations is small and their angular range is not entirely coincident with those from quantum mechanics and experiment. Classical dynamics, even including attractive interactions, cannot account properly for the mentioned oscillatory behaviour. Secondary encounters between the outgoing Ar atom and NO molecule, giving rise to 'chattering', are found to be relatively frequent, leading to a decrease in the final rotational energy of NO with respect to that attained in the first encounter. Chattering trajectories are defined and their mechanism is characterized. © Royal Society of Chemistry ; Funded by the Ministry of Science and Technology of Spain under grants BQU2002-04627-C02 and REN 2000-1557 and by the European Union through the RTN Reaction Dynamics(HPRN-CT-1999-0007). The research was performed within the Unidad Asociada ''Química Física Molecular'' between the Universidad Complutense and the CSIC. ; Peer Reviewed

9 p.: gráf. ; Integral cross sections and thermal rate constants have been calculated for the N 2D +H2 reaction and its isotopic variants N 2D +D2 and the two-channel N 2D +HD by means of quasiclassical trajectory and statistical quantum-mechanical model methods on the latest ab initio potential-energy surface T.-S. Ho et al., J. Chem. Phys. 119, 3063 2003 . The effect of rotational excitation of the diatom on the dynamics of these reactions has been investigated and interesting discrepancies between the classical and statistical model calculations have been found. Whereas a net effect of reagent rotation on reactivity is always observed in the classical calculations, only a very slight effect is observed in the case of the asymmetric N 2D +HD reaction for the statistical quantum-mechanical method. The thermal rate constants calculated on this Potential-Energy Surface using quasiclassical trajectory and statistical model methods are in good agreement with the experimental determinations, although the latter are somewhat larger. A reevaluation of the collinear barrier of the potential surface used in the present study seems timely. Further theoretical and experimental studies are needed for a full understanding of the dynamics of the title reaction. © 2005 American Institute of Physics. ; Financial support through the Ramón y Cajal program from the Spanish Ministry of Education and Science. This work has been funded by the Ministry of Education and Science of Spain under Grant Nos. BQU2002-04627-C02-02, FTN2003-08228-CO3-03, and FIS2004-02461 and CAM 07N/0058/2002 and by the European Union through the RTN Reaction Dynamics HPRN-CT-1999-0007 and Project No. MERGCT-2004-513600. The research was performed within the Unidad Asociada "Química Física Molecular" between the Universidad Complutense and the CSIC. ; Peer reviewed

The rotationally inelastic scattering of NO by Ar was studied on a potential energy surface at the collision energy of a high resolution experiment. The study entailed the calculationm of the state-resolved integral and differential cross sections for all the excited levels of NO in the lowest spin-orbit manifold. The quasiclassical approach was shown to satisfactorily reproduce few observations seen in both the experimental and quantum mechanical state-resolved differential cross-sections. © 2003 American Institute of Physics ; Funded by the Ministry of Science and Technology of Spain under Grants No. BQU2002-04627-C02 and No. REN 2000-1557, by the European Union through the RTN Reaction Dynamics ~HPRN-CT-1999-0007!, and by the U.S. National Science Foundation ~Grant No. CHE-9971810! The research was performed within the Unidad Asociada ''Química Física Molecular'' between the Universidad Complutense and the CSIC. ; Peer Reviewed

Methyl isocyanate (CH3NCO) was recently found in hot cores and suggested to exist on comet 67P/CG. The incorporation of this molecule into astrochemical networks requires data on its formation and destruction. In this work, ices of pure CH3NCO and of CH3NCO(4%–5%)/H2O mixtures deposited at 20 K were irradiated with a UV D2 lamp (120–400 nm) and bombarded by 5 keV electrons to mimic the secondary electrons produced by cosmic rays (CRs). The destruction of CH3NCO was studied using IR spectroscopy. After processing, the νa–NCO band of CH3NCO disappeared and IR bands corresponding to CO, CO2, OCN−, and HCN/CN− appeared instead. The products of photon and electron processing were very similar. Destruction cross sections and half-life doses were derived from the measurements. Water ice provides a good shield against UV irradiation (half-life dose of ∼64 eV molecule−1 for CH3NCO in water ice), but is not so good against high-energy electrons (half-life dose ∼18 eV molecule−1). It was also found that CH3NCO does not react with H2O over the temperature range 20–200 K. These results indicate that hypothetical CH3NCO in the ices of dense clouds should be stable against UV photons and relatively stable against CRs over the lifetime of a cloud (∼107 yr), and could sublime in the hot core phase. On the surface of a Kuiper Belt object (the original location of comet 67P/CG) the molecule would be swiftly destroyed, by both photons and CRs, but embedded below just 10 μm of water ice, the molecule could survive for ∼109 yr. ; This work has been funded by the Spanish MINECO under grants FIS2013-48087-C2-1P, FIS2016-C3-1P, and AYA2016- 75066-C2-1-P. J.-C.G. and J.C. also thank the ANR-13-BS05- 0008 IMOLABS and J.-C.G. thanks the Program PCMI (INSU-CNRS) and the Centre National d'Etudes Spatiales (CNES) for funding support. European Union funding under grant ERC-2013-Syg 610256 (NANOCOSMOS) is also acknowledged. ; Peer reviewed

9 pags., 5 figs., 6 tabs. ; Methyl isocyanate has been recently detected in comet 67P/Churyumov–Gerasimenko (67P/CG) and in the interstellar medium. New physicochemical studies on this species are now necessary as tools for subsequent studies in astrophysics. In this work, infrared spectra of solid CH3NCO have been obtained at temperatures of relevance for astronomical environments. The spectra are dominated by a strong, characteristic multiplet feature at 2350–2250 cm−1, which can be attributed to the asymmetric stretching of the NCO group. A phase transition from amorphous to crystalline methyl isocyanate is observed at ∼90 K. The band strengths for the absorptions of CH3NCO in ice at 20 K have been measured. Deuterated methyl isocyanate is used to help with the spectral assignment. No X-ray structure has been reported for crystalline CH3NCO. Here we advance a tentative theoretical structure, based on density functional theory (DFT) calculations, derived taking the crystal of isocyanic acid as a starting point. A harmonic theoretical spectrum is then calculated for the proposed structure and compared with the experimental data. A mixed ice of H2O and CH3NCO was formed by simultaneous deposition of water and methyl isocyanate at 20 K. The absence of new spectral features indicates that methyl isocyanate and water do not react appreciably at 20 K, but form a stable mixture. The high CH3NCO/H2O ratio reported for comet 67P/CG, and the characteristic structure of the 2350–2250 cm−1 band, makes it a very good candidate for future astronomical searches. ; This work was funded by the European Union under grant ERC-2013-Syg 610256 (NANOCOSMOS) and by the Spanish MINECO CSD2009-00038 (ASTROMOL) within the Consolider–Ingenio Program. MINECO funding from grants FIS2013-48087-C2-1P, FIS2016-C3-1P, AYA2012- 32032 and AYA2016-75066-C2-1-P is also acknowledged. G. M. acknowledges MINECO PhD grant BES-2014-0693. JCG and JC also thank the ANR-13-BS05-0008 IMOLABS and JCG thanks the Program PCMI (INSU-CNRS) and the Centre National d'Etudes Spatiales (CNES) for funding support ; Peer reviewed

10 pags., 9 figs., 2 tabs. ; Interstellar (IS) dust analogs, based on amorphous hydrogenated carbon (a-C:H) were generated by plasma deposition in radio frequency discharges of CH4 + He mixtures. The a-C:H samples were characterized by means of secondary electron microscopy, infrared (IR) spectroscopy and UV-visible reflectivity. DFT calculations of structure and IR spectra were also carried out. From the experimental data, atomic compositions were estimated. Both IR and reflectivity measurements led to similar high proportions (≈50%) of H atoms, but there was a significant discrepancy in the sp2/sp3 hybridization ratios of C atoms (sp2/sp3 = 1.5 from IR and 0.25 from reflectivity). Energetic processing of the samples with 5 keV electrons led to a decay of IR aliphatic bands and to a growth of aromatic bands, which is consistent with a dehydrogenation and graphitization of the samples. The decay of the CH aliphatic stretching band at 3.4 μm upon electron irradiation is relatively slow. Estimates based on the absorbed energy and on models of cosmic ray (CR) flux indicate that CR bombardment is not enough to justify the observed disappearance of this band in dense IS clouds. ; This work was funded by the Spanish MINECO under grants FIS2013-48087-C2-1P and FIS2016-77726-C3-1P. European Union funding under the project ERC-2013-Syg 610256 (NANOCOSMOS) is also acknowledged. ; Peer reviewed

13 pags., 8 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0 ; The increasing demand for nanostructured materials is mainly motivated by their key role in a wide variety of technologically relevant fields such as biomedicine, green sustainable energy or catalysis. We have succeeded to scale-up a type of gas aggregation source, called a multiple ion cluster source, for the generation of complex, ultra-pure nanoparticles made of different materials. The high production rates achieved (tens of g/day) for this kind of gas aggregation sources, and the inherent ability to control the structure of the nanoparticles in a controlled environment, make this equipment appealing for industrial purposes, a highly coveted aspect since the introduction of this type of sources. Furthermore, our innovative UHV experimental station also includes in-flight manipulation and processing capabilities by annealing, acceleration, or interaction with background gases along with in-situ characterization of the clusters and nanoparticles fabricated. As an example to demonstrate some of the capabilities of this new equipment, herein we present the fabrication of copper nanoparticles and their processing, including the controlled oxidation (from Cu to CuO through CuO, and their mixtures) at different stages in the machine. ; This work was supported by the European Union [grant number ERC-2013-SyG 610256 NANOCOSMOS]; the Spanish MINECO [grant numbers MAT2017-85089-C2-1-R, MAT2014-54231-C4-1-P, MAT2014-54231- C4-4-P, MAT2014-59772-C2-2-P, FIS2016-77578-R, FIS2013-48087-C2-1P, FIS2016-77726-C3-1P and CSIC13-4E-1775]. ; Peer Reviewed

I. Tanarro et al. -- 16 pags., 18 figs., app. ; We present a proof of concept on the coupling of radio astronomical receivers and spectrometers with chemical reactors and the performances of the resulting setup for spectroscopy and chemical simulations in laboratory astrophysics. Several experiments including cold plasma generation and UV photochemistry were performed in a 40 cm long gas cell placed in the beam path of the Aries 40 m radio telescope receivers operating in the 41–49 GHz frequency range interfaced with fast Fourier transform spectrometers providing 2 GHz bandwidth and 38 kHz resolution. The impedance matching of the cell windows has been studied using di erent materials. The choice of the material and its thickness was critical to obtain a sensitivity identical to that of standard radio astronomical observations. Spectroscopic signals arising from very low partial pressures of CH3OH, CH3CH2OH, HCOOH, OCS, CS, SO2 (<103 mbar) were detected in a few seconds. Fast data acquisition was achieved allowing for kinetic measurements in fragmentation experiments using electron impact or UV irradiation. Time evolution of chemical reactions involving OCS, O2 and CS2 was also observed demonstrating that reactive species, such as CS, can be maintained with high abundance in the gas phase during these experiments ; The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC-SyG-2013 Grant Agreement No. 610256 NANOCOSMOS and from spanish MINECO CSD2009-00038 (ASTROMOL) under the Consolider-Ingenio Program. We also thank spanish MINECO for funding under grants AYA2012-32032, AYA2016-75066-C2-1-P, FIS2013-48087-C2-1-P, FIS2016-77726-C3-1-P, FIS2016-77578-R, MAT2014- 54231-C4-1-P. ; Peer reviewed