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DNA origami nanostructures are emerging as a bottom-up nanopatterning approach. Direct combination of this approach with top-down nanotechnology, such as ion beams, has not been considered because of the soft nature of the DNA material. Here we demonstrate that the shape of 2D DNA origami nanostructures deposited on Si substrates is well preserved upon irradiation by ion beams, modeling ion implantation, lithography, and sputtering conditions. Structural changes in 2D DNA origami nanostructures deposited on Si are analyzed using AFM imaging. The observed effects on DNA origami include structure height decrease or increase upon fast heavy ion irradiation in vacuum and in air, respectively. Slow- and medium-energy heavy ion irradiation results in the cutting of the nanostructures or crater formation with ion-induced damage in the 10 nm range around the primary ion track. In all these cases, the designed shape of the 2D origami nanostructure remains unperturbed. Present stability and nature of damages on DNA origami nanostructures enable fusion of DNA origami advantages such as shape and positioning control into novel ion beam nanofabrication approaches.

This retrospective study examined clinical parameters associated with amantadine treatment of psychiatric symptoms in children. A total of 297 pediatric patients were prescribed amantadine and met study criteria to assess clinical responses and medication outcomes. More than 62% of patients experienced clinically significant symptom control and 83% achieved at least maintenance symptom control, while 11% discontinued amantadine for nonresponse and 6% stopped amantadine because of side effects. Among patients previously receiving other psychotropic medication, 42% and 28% of patients fully discontinued second- or third-generation antipsychotics or antidepressants, respectively. Patients responsive to amantadine who discontinued or reduced antipsychotic dose experienced a significant reduction in body mass index. Amantadine appears be an efficacious and safe alternative for treatment of a broad set of psychiatric symptoms in children and adolescents. Specifically, it may serve as an effective adjunct to stimulants for attention deficit/hyperactivity disorder-related symptoms and appears to be a safer alternative to second- or third-generation antipsychotics.

We performed experiments of implantation of energetic sulfur ions (105 keV) into 2:1 water:propane ices at 80 K and analyzed the resulting refractory organic matter with ultrahigh-resolution mass spectrometry. Our goal was to characterize the organic matter processed in the surface conditions of Europa, where it would receive a heavy flux of energetic particles, including sulfur ions, and determine whether organosulfurs could be formed in these conditions, using the simplest alkane that can exist in solid form on Europa’s surface. We find that the produced organic matter contains a large variety of both aliphatic and aromatic compounds (several thousand unique formulae), including polycyclic aromatic hydrocarbons (PAHs), with masses up to 900 amu. A large number of aromatic hydrocarbons is found along with oxygenated, mostly aliphatic, compounds. Organosulfurs are found in both CHS and CHOS form, demonstrating they can be formed from any organic compound through sulfur implantation. These organosulfurs’ properties (aromaticity, mass) appear similar to the rest of the organic matter, albeit their low quantity does not allow for a thorough comparison. Our results have implications for the type of refractory organic matter that could be observed by the JUICE and Europa Clipper space missions and how the surface of Europa could generate complex organics, including PAHs and organosulfurs, that could then enrich the subsurface ocean. In particular, they indicate that a large diversity of organic matter, including organosulfurs, can be formed from simple precursors in a geologically short time frame under the ion flux that reaches Europa.

Aims. Astrophysical ices on dust grain mantles in the interstellar medium (ISM) and dense circumstellar envelopes (CSEs) are continuously exposed to galactic cosmic rays (GCRs). In a laboratory setting, we studied the physical and chemical modifications of ice layers induced by energetic heavy ions as GCR analogues. The ice layers used have a molecular composition similar to that of icy grain mantles. Methods. Mixtures of H2O:CO:CH3OH molecules (percentages 73:24:3, 68:30:3, and 58:38:3) were condensed on a substrate at 15 K and irradiated with 40 MeV 58Ni11+ ion beams. Irradiation-induced modifications were followed using the mid-infrared absorption spectroscopy technique. Results. We observed the evolution of infrared bands of CO2, HCO, HCOOH, CH4, H2CO,H2O2, and more complex synthesised molecules. From the molecular column densities, cross-sections and sputtering yields were determined and compared to published results of water and carbon monoxide. Analysis of the chemical modifications reveals that the precursors are easily destroyed when they are in a molecular mixture, while others are desorbed. Conclusions. The main radiolitic modifications induced by GCR irradiations are molecular decomposition and sputtering. Extrapolation to astrophysical radiation conditions shows a strong dependence on the intensity of the GCR distributions at low energies, which allows the analysis of the ice evolution at timescales comparable to those of the ISM and CSE. [ABSTRACT FROM AUTHOR]

Radiolysis of α-pinene by 61.3 MeV 84Kr15 + ions was analysed with the scope to simulate the effects of heavy ion cosmic ray bombardment on chiral molecules in the interstellar medium. The α-pinene ice samples were irradiated at 10 K and their chemical evolution was monitored by mid-infrared Fourier transform (FTIR) spectroscopy to characterize the reaction products and to determine the extent of racemization. The integrated band strengths have been obtained for all the neutral α-pinene vibrational bands using the experimental band integrated absorbances and the theoretical absolute intensities calculated along the column densities. In the current heavy ion bombardment experiments, small molecules were formed and the precursor, α-pinene, was destroyed instead of being racemized. Twelve hydrocarbons were produced (final fluence of 2.0 × 1012 ions cm−2): methane (CH4), acetylene (C2H2), ethylene (C2H4), propylene (C3H6), propane (C3H8), n-butane (C4H10), butene (C4H8), propyne (C3H4), benzene (C6H6), ethane (C2H6), vinylacetylene (C4H4), and 2-methyl-1,3-butadiene or isoprene (C5H8). The highest formation cross-section (∼ 40 × 10−15 cm2) was observed for the C3H4 and the lowest was for C3H8 (∼ 3 × 10−15 cm2). The radiochemical yields for these molecules follow the same trends as those of their cross-sections. The atom budget calculation confirms that all the expected products have been generated during the radiolysis and supports the conclusion that the proposed A values are accurate. The α-pinene sputtering yield for this ion beam was found to be Y0  = 1.84 × 106 molecules per impact. [ABSTRACT FROM AUTHOR]

This is the story of Lily, a 12-year-old girl with Williams Syndrome (WS). A reading program was developed to meet Lily's specific reading needs while addressing her individual learning style; this includes attending to the unique characteristics of Williams Syndrome. During this school year, Lily showed significant gains in sight word recognition and comprehension with the implementation of a personalized balanced reading program. (Contains 5 tables.)

Carbon monoxide (CO) plays a vital role in interstellar chemistry, existing abundantly in both gaseous and frozen environments. Understanding the radiation-driven chemistry of CO-rich ices is crucial for comprehending the formation and desorption of C-bearing molecules in the interstellar medium (ISM), particularly considering the potential impact of temperature on these processes. We report experimental data on irradiation processing of pure CO ice by cosmic ray analogues (95.2 MeV 136Xe23+ ions) at temperatures of 10, 15, and 20 K, in the IGLIAS set-up coupled to the IRRSUD beamline at GANIL (Caen, France). The evolution of the irradiated frozen samples was monitored by infrared spectroscopy. The computational PROCODA code allows us to quantify the chemical evolution of the samples, determining effective reaction rates coefficients (ERCs), molecular abundances at the chemical equilibrium (CE) phase, and desorption processes. The model integrated 18 chemical species – 8 observed (CO, CO2, C3, O3, C2O, C3O, C3O2, and C5O3) and 10 non-observed but predicted (C, O, C2, O2, CO3, C4O, C5O, C2O2, C2O3, C4O2) – linked via 156 reactions. Our findings reveal temperature-driven influences on molecular abundances at chemical equilibrium, desorption yields and rates, and ERC values. Certain reaction routes exhibit distinct thermochemical behaviours of gas- and ice-phase reactions which may be attributed to the presence of neighbouring molecules within the ice matrix. This study provides pivotal insights into the chemical evolution of CO-enriched ice under irradiation, impacting solid-state astrochemistry, clarifying molecular abundances, and advancing our understanding of ISM chemistry and temperature effects on ionized radiation-processed frozen ices. [ABSTRACT FROM AUTHOR]

This article investigates the radiolysis of a mixture of nitric acid with water (HNO3:H2O) at 16 K in high-vacuum (residual pressure < 10−6 mbar). A nitric acid-water ice film was exposed to 40 MeV 58Ni11+ ion beam in a heavy ion accelerator facility in France. For this astrochemically- and atmospherically-relevant ice mixture of nitric acid and water, we analyze the possible formation and destruction processes of N–O bearing species, thus providing spectroscopic data in the infrared (IR) region for theoretical, laboratory and observational future studies. The irradiation synthetized 18 species which were posteriorly examined by infrared spectroscopy: N2O, NH3, NO, NO2 and H x N y O z molecules, such as hidroxylamine (NH2OH), nitrous acid (HONO) as well as other species with bonding N–O, N–H and H–O–N converting surface-adsorbed nitrogen oxides into astrochemically active NO x. The interaction of HNO3 and H2O originates H–N–O molecular complexes, which were investigated as particular cases of the hydrogen-bonded species formed by a more electronegative atom (N or O) interacts intra or intermolecularly with a donor atom (N or O) and observed in the interstellar medium with higher quantities or great abundances. The HNO3 and H2O destruction cross sections have been determined to be 8.5 × 10−13 and 1.2 × 10−13 cm2, respectively, for the mentioned experimental conditions. [ABSTRACT FROM AUTHOR]

Radiolysis of biomolecules by fast ions has interest in medical applications and astrobiology. The radiolysis of solid D-valine (0.2−2 μm thick) was performed at room temperature by 1.5 MeV H+, He+, N+, and 230 MeV S15+ ion beams. The samples were prepared by spraying/dropping valine-water-ethanol solution on ZnSe substrate. Radiolysis was monitored by infrared spectroscopy (FTIR) through the evolution of the intensity of the valine infrared 2900, 1329, 1271, 948, and 716 cm−1 bands as a function of projectile fluence. At the end of sample irradiation, residues (tholins) presenting a brownish color are observed. The dependence of the apparent (sputtering + radiolysis) destruction cross section, σd, on the beam stopping power in valine is found to follow the power law σd = aSen, with n close to 1. Thus, σd is approximately proportional to the absorbed dose. Destruction rates due to the main galactic cosmic ray species are calculated, yielding a million year half-life for solid valine in space. Data obtained in this work aim a better understanding on the radioresistance of complex organic molecules and formation of radioproducts.

Neste trabalho, estudamos a estabilidade da molécula de glicina na sua forma zwiteriônica cristalina, conhecida como a-glycina (+NH3CH2COO-) a duas temperaturas (14 e 300 K), sob a ação de íons rápidos, simulando ambientes espaciais na presença de raios cósmicos pesados. Para tanto, a meia vida da glicina bombardeada no meio interestelar (nuvens densas) foi estimada, sendo 1.1 x 104 anos (300 K) e 1.6 x 103 anos (14 K). No sistema solar, os valores foram de 1.2 x 103 anos (300 K) e 2.8 x 103 anos (14 K). O estudo da estabilidade da glicina, nesses ambientes, traz à tona questões sobre o papel dessa molécula na química pré-bióticana Terra, para auxiliar nas descobertas sobre a origem da vida como a conhecemos.

Aims. With this article, we aim to provide the sputtering yields for molecular species of potential astrophysical interest and in the electronic regime of interaction characteristic of cosmic rays. We specifically target molecules that are constitutive of interstellar ice mantles. Methods. We used a compendium of existing data on electronic sputtering to calculate the prefactors leading to the generalisation of the stopping-power-dependent sputtering yield for many species condensing at low temperature. In addition, we present new experimental results to constrain the yield for solid CH4, C6, and CH3CN. Results. Electronic sputtering is constrained using literature data for H2, HD, D2, Ne, N2, CO, Ar, O2, Kr, Xe, CO2, SO2, NH3, S, H2O, D2O, CH3OH, Leucine, C20H12, C24H12, and C60. A first-order relation with the sublimation enthalpy is derived, which allows us to predict the sputtering yield within an order of magnitude for most species. The fluctuations around the mean are partly assignable to the differences in resilience towards radiolysis for individual species, and partly to the micro-physics details of the energy transfer to the lattice. [ABSTRACT FROM AUTHOR]

Water ices at 15 and 144 K were bombarded by swift heavy ions, 45.8 MeV 58Ni11 + and 606 MeV 64Zn26 +, to measure the induced chemical and physical effects. The column densities of water and the synthesized species, hydrogen peroxide (H2O2) and ozone (O3), were monitored via infrared spectroscopy. The formation and destruction cross-sections of precursor and products were determined and compared with literature. The H2O2 formation and destruction cross-sections  reveal a linear dependence with electronic stopping power, σ ∝  S e. The sputtering yield (Y 0) shows a power law with electronic energy lost, |$Y_0\propto S_\mathrm{e}^2$|⁠ , and an exponential increase with the sample temperature. The findings indicate that the radiolysis rate of water ice is higher at low temperatures while the desorption yield increases at higher temperatures. A large amount of water ice is located in the grain mantles of the circumstellar envelopes and the interstellar medium regions, which are exposed to galactic cosmic rays (GCRs). The synthesis of H2O2 and O3 molecules as a function of absorbed doses of GCR irradiation and their irradiation time is analysed in detail. Besides, the extrapolation of the sputtering yield rates, as a function of time and temperature, for astrophysical conditions can contribute to a better understanding of non-thermal sputtering of water ices. [ABSTRACT FROM AUTHOR]

H2O:CO, at concentrations of (3:2) and (10:1), was condensed on CsI substrate at 15 K and irradiated with 46-MeV 58Ni11 + ion beam. Radiolysis induced by fast heavy ions was analyzed by infrared spectroscopy (FTIR). The formation of nine molecular species: CO2, H2O2, HCOOH, HCO, H2CO, 13CO2, CH3OH, O3, and C3O2 was observed. For both concentrations, carbon dioxide (CO2), formaldehyde (H2CO), formic acid (HCOOH), and hydrogen peroxide (H2O2) are the most abundant products species, and tricarbon dioxide (C3O2) is much less abundant. Precursor destruction cross-sections and formation cross-sections of products are determined. The CO destruction cross-section for the (3:2) concentration is almost five times higher than that of water, while those for the (10:1) concentration are practically the same. Atomic sputtering yields are estimated for the two ice films, the total mass sputtered is approximately 2.5 × 106 u per impact. These results contribute to figure out the chemical pathways of compounds synthesized from the two most abundant organic species (H2O and CO) observed in the ices of grain mantles of the circumstellar envelopes and interstellar medium. In additional, the finding results reveal that molecular astronomical percentages are comparable to those obtained after 15 eV molec−1 of deposited dose in current experiments compared with the relative concentration of molecules in solid phase observed in MYSO, LYSO, BG Stars, and Comets. [ABSTRACT FROM AUTHOR]

Our groups in Brazil, France and Italy have been active, among others in the world, in performing experiments on physical-chemical effects induced by fast ions colliding with solids (frozen gases, carbonaceous and organic materials, silicates, etc.) of astrophysical interest. The used ions span a very large range of energies, from a few keV to hundreds MeV. Here we present a summary of the results obtained so far on the formation of oxidants (hydrogen peroxide and ozone) after ion irradiation of frozen water, carbon dioxide and their mixtures. Irradiation of pure water ice produces hydrogen peroxide whatever is the used ion and at different temperatures. Irradiation of carbon dioxide and water frozen mixtures result in the production of molecules among which hydrogen peroxide and ozone. The experimental results are discussed in the light of the relevance they have to support the presence of an energy source for biosphere on Europa and other icy moons in the outer Solar System.

The interstellar chemistry of nitrogen is considerably less understood than the chemistry of other common elements, such as carbon and oxygen. Even though a relatively large number of species containing nitrogen atoms have already been detected in the interstellar medium, only six of them bear a nitrogen–oxygen (N–O) bond. Some astrophysical and primeval Earth models suggest that N–O species, such as hydroxylamine (NH2OH), are potential precursors of prebiotic amino acids, and even peptides. In this work, we have analyzed an apolar ice mixture of N2:CO of astrophysical interest to investigate possible formation mechanisms of N–O bearing molecules due to processing of the sample by 64Ni24+ 538 MeV ions (8.4 MeV/u) at 14 K. The results show the formation of simple nitrogen oxides (⁠|$\rm {N_{1 - 2}}{O_y})$|⁠ , but no CN–O species of any kind. We have also determined the formation cross-sections of some of the products, as well as the destruction cross-sections of precursors and products. The results presented here are discussed in light of our previous work on the processing of a NH3:CO ice mixture, which have found no N–O bearing molecules at all. [ABSTRACT FROM AUTHOR]

H2O and CO molecules are the main constituents of the interstellar dust grain ice mantles. Infrared spectra of the ices in line of sights of young stellar objects and background stars have shown that the CO stretching vibration band can be decomposed into three main components: 2143, 2139, and 2136 cm−1, assigned to CO in different environment sites. The relative strengths between the components have been associated with an evolutionary track of the interstellar molecular clouds. H2O:CO (3:2) and (10:1) ice samples were irradiated by 0.79 MeV/u 58Ni13+ ions to simulate the effects produced by heavy ion cosmic rays in typical interstellar ice mixtures. The CO stretching vibration band is decomposed into six Gaussian functions (2150, 2144, 2141, 2138, 2136, and 2133 cm−1) and their integrated absorbances were measured as a function of fluence. The results show that, at the final fluence, the component 2138 cm−1 is the main component of the CO stretching vibration band. The component 2150 cm−1 disappears at the beginning of irradiation. Based on the present and previous results, a time-scale for the components in the interstellar ices is proposed. For H2O:CO ices in the interstellar medium, it is predicted that, after 1 Ma, the main components of the CO stretching vibration band are the 2138 and 2141 cm−1, due to the CO monomers and dimers, respectively. [ABSTRACT FROM AUTHOR]

Experimental results on the processing of NH3:CO ice mixtures of astrophysical relevance by energetic (538 MeV 64Ni24+) projectiles are presented. NH3 and CO are two molecules relatively common in interstellar medium and Solar system; they may be precursors of amino acids. 64Ni ions may be considered as representative of heavy cosmic ray analogues. Laboratory data were collected using mid-infrared Fourier transform spectroscopy and revealed the formation of ammonium cation (NH |$_4^+$|⁠), cyanate (OCN−), molecular nitrogen (N2), and CO2. Tentative assignments of carbamic acid (NH2COOH), formate ion (HCOO−), zwitterionic glycine (NH |$_3^+$| CH2COO−), and ammonium carbamate (NH |$_4^+$| NH2COO−) are proposed. Despite the confirmation on the synthesis of several complex species bearing C, H, O, and N atoms, no N–O-bearing species was detected. Moreover, parameters relevant for computational astrophysics, such as destruction and formation cross-sections, are determined for the precursor and the main detected species. Those values scale with the electronic stopping power (S e) roughly as σ ∼ a S |$_\mathrm{ e}^n$|⁠ , where n ∼ 3/2. The power law is helpful for predicting the CO and NH3 dissociation and CO2 formation cross-sections for other ions and energies; these predictions allow estimating the effects of the entire cosmic ray radiation field. [ABSTRACT FROM AUTHOR]

The processing of H2O:CO2:CH4 (10:1:1) and H2O:CO2:CH4:NH3 (10:1:1:1) ices at 72 K by oxygen ions was studied in an attempt to simulate the physicochemical effects induced by energetic ions on the surface of Enceladus (or similar cold surfaces in the outer Solar System). The experiments were carried out at the Grand Accélérateur National d'Ions Lourds (GANIL) in Caen/France. The samples were irradiated with 15.7-MeV O5+ at the IRRadiation SUD (IRRSUD) beamline and with 108-keV O6+ at the Accélérateurs pour les Recherches avec les Ions de Basses Energies (ARIBE) beamline. The frozen samples were monitored by Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy (4000–650 cm−1, 2.5–15.4 μm, at 1 cm−1 resolution). The identified molecular species formed during irradiation were CO, OCN−, CH3OH, HCN, CN−, H2CO3, HNCO, HCO and CO3. The effective formation cross-sections for the synthesis of new species and the effective molecular destruction cross-sections of the parent species in the experiments with MeV ions were found to be of the order of 10−14–10−13 cm2. For the keV ion experiments, these values were of the order of 10−16–10−15 cm2. The fluence at which the sample reaches chemical equilibrium and the molecular abundances in this region (equilibrium branching ratios) were estimated. These experiments suggest that the chemical inventory on the surface of Enceladus can be influenced by the incidence of charged particles on to the moon's surface. [ABSTRACT FROM AUTHOR]

Physico-chemical modifications induced by swift heavy ions on methane-water (CH4:H2O) ices at 15 K are analyzed. Ice films, at concentrations of (1:3) and (1:15), were irradiated by 40 MeV 58Ni11+ ions. Fourier transform transmission spectroscopy in the mid-range was used to monitor the evolution ices at 15 K as a function of projectile fluence. New IR bands appearing for the irradiated (CH4:H2O) (1:3) ice are attributed to the synthesized molecules: C3H8, HCO, H2CO, CO, CO2, H2O2, HCOOH, CH3OH, C2H5OH, and CH3CHO. For the irradiated (CH4:H2O) (1:15) ice, the abundances of the compounds containing two carbons atoms are lower than those for the (1:3) ice; in contrast, CH3OH and H2O2 abundances increase when compared to the values obtained with the (1:3) ice. After irradiation, the ices were warmed up until 110 K, when the IR spectra reveal features of complex organic molecules. The destruction and formation cross sections and the sputtering yields of the ice mixtures are estimated. These findings provide possible pathways for the occurrence of compounds rich in C, O, and H, which are indeed observed in the cold regions of the universe such as ices in grain mantles of the interstellar medium and circumstellar envelopes. [ABSTRACT FROM AUTHOR]

Context. Micrometeorites represent, at timescales shorter than a few million years, the dominant source of extraterrestrial matter at the surface of the Earth. Analyses of ultracarbonaceous micrometeorites recovered from Antarctica, known as UCAMMs reveal an exceptionally N-rich organic matter associated with spatially extended high D enrichments. Experiments show that this specific organic matter might have been formed in the outer solar system by energetic irradiation of N-rich icy surfaces. Aims. We experimentally investigate the hydrogen isotopic fractionation resulting from irradiation of normal and D-rich N2-CH4 ices by high energy ions, simulating the exposition to Galactic cosmic rays of icy bodies surfaces orbiting at large heliocentric distances. Methods. Films of N2-CH4 ices and a N2-CH4/CD4/N2-CH4 "sandwich" ice were exposed to 129Xe13+ ion beams at 92 and 88 MeV. The chemical evolution of the samples was monitored using in situ Fourier transform infrared spectroscopy. After irradiation, targets were annealed to room temperature. The solid residues of the whole process left after ice sublimation were characterized in situ by infrared spectroscopy, and the hydrogen isotopic composition measured ex situ by imaging secondary ion mass spectrometry at the sub-micron scale (NanoSIMS). Results. Irradiation leads to the formation of new molecules and radicals. After annealing, the resulting poly-HCN-like macro-molecular residue exhibits an infrared spectrum close to that of UCAMMs. The residue resulting from irradiation of N2-CH4 ices does not exhibit a significant deuterium enrichment comparable to that found in extraterrestrial organic matter. The residue formed by irradiation of D-rich ices shows the formation of isotopic heterogeneities with localised hotspots and an extended contribution likely due to the diffusion of the radiolytic products from the D-rich layer. Conclusions. These results show that high-energy cosmic ray irradiation does not induce the large hydrogen isotopic fractionation observed at small spatial scale in interplanetary organics. By contrast, large D/H ratio heterogeneities at the sub-micron spatial scale in extraterrestrial organic matter can result from isotopically heterogeneous ices mixtures (i.e. condensed with different D/H ratios), which were transformed into refractory organic matter upon irradiation. [ABSTRACT FROM AUTHOR]

Context. The occurrence of complex organic molecules (COMs) in the gas phase at low temperature in the dense phases of the interstellar medium suggests that a non-thermal desorption mechanism is at work because otherwise, COMs should condense within a short timescale onto dust grains. Vacuum ultraviolet (VUV) photodesorption has been shown to be much less efficient for complex organic molecules, such as methanol, because mostly photoproducts are ejected. The induced photolysis competes with photodesorption for large COMs, which considerably lowers the efficiency to desorb intact molecules. Aims. We pursue an experimental work that has already shown that water molecules, the dominant ice mantle species, can be efficiently sputtered by cosmic rays. We investigate the sputtering efficiency of complex organic molecules that are observed either in the ice mantles of interstellar dense clouds directly by infrared spectroscopy (CH3OH), or that are observed in the gas phase by millimeter telescopes (CH3COOCH3) and that could be released from interstellar grain surfaces. Methods. We irradiated ice films containing complex organic molecules (methanol and methyl acetate) and water with swift heavy ions in the electronic sputtering regime. We monitored the infrared spectra of the film as well as the species released to the gas phase with a mass spectrometer. Results. We demonstrate that when methanol or methyl acetate is embedded in a water-ice mantle exposed to cosmic rays, a large portion is sputtered as an intact molecule, with a sputtering yield close to that of the main water-ice matrix. This must be even more true for the case of more volatile ice matrices, such as those that are embedded in carbon monoxide. Conclusions. Cosmic rays penetrating deep into dense clouds provide an efficient mechanism to desorb complex organic molecules. Compared to the VUV photons, which are induced by the interaction of cosmic rays, a large portion desorb as intact molecules with a proportion corresponding to the time-dependent bulk composition of the ice mantle, the latter evolving with time as a function of fluence due to the radiolysis of the bulk. [ABSTRACT FROM AUTHOR]

We designed and built a mobile experimental set-up for studying the interaction of ion beams with solid samples in a wide temperature range from 9 to 300 K. It is either possible to mount up to three samples prepared ex situ or to prepare samples by condensation of molecules from gases or vapours onto IR or Visible-ultraviolet (Vis-UV) transparent windows. The physico-chemical evolution during irradiation can be followed in situ with different analysis techniques including Fourier transform infrared spectroscopy, Vis-UV, and quadrupole mass spectrometry. [ABSTRACT FROM AUTHOR]