Unusual hydrogen and hydroxyl migration in the fragmentation of excited doubly-positively-charged amino acids in the gas phase

We present a combined experimental and theoretical study of the fragmentation of doubly-positively- charged amino acids in the gas phase. The combination of ab initio molecular dynamics simulations with ion- molecule collisions followed by multiple-coincidence mass spectrometric techniques, allows us to obtain a complete picture of the fragmentation dynamics. In addition to the expected Coulomb explosion, we have found evidence of hydrogen and hydroxyl-group migration processes, which leads to unusual fragmentation product

Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System

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.This research has been supported by the European COST Action CM0805: The Chemical Cosmos.Boduch, P.; Da Silveira, EF.; Domaracka, A.; Gomis Hilario, O.; Lv, XY.; Palumbo, ME.; Pilling, S.... (2011). Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System. Advances in Astronomy. 1-10. doi:10.1155/2011/327641S11

Slow ion interaction with N-methylglycine and N-acetylglycine

N-acetyl glycine and N-methyl glycine molecules in the gas phase are ionized by electron exchange with slow O6+ ions at an energy of 48 keV. After ionization, the methyl and acetyl substituted glycines dissociate into fragments analogous to that resulting from ionization and fragmentation of amino acids and peptides, respectively. N-acetylglycine which contains a peptide bond also effectively tautomerizes to the diol form. Such tautomerization is typical for amino acids, however, we show that the tautomerization mechanism of the N-acetylglycine is differen

Fusion reaction dynamics of fullerene molecules

Systematic molecular dynamics simulations based on the self-consistent charge density functional tight-binding method have been performed for the molecular collisions inside clusters of fullerene molecules, after prompt atom knockouts by the keV ions. The thermodynamic and kinetic stabilities, as well as the bonding features, have been investigated for the most stable dumbbell dimers C+118, C+119 and C+12

Charge and energy flows in ionised thymidine

We present a combined experimental and theoretical study of the ionisation and fragmentation of the nucleoside thymidine in the gas phase. Two sources of ionisation/excitation are used, namely UV photons and low-energy multiply charged ions, associated with coincidences measurements, respectively photoelec- tron/photofragment (PEPICO) and fragment/fragment. Coupling these experiments with quantum chemistry calculations, we obtain a complete picture of the fragmentation dynamics, in particular the charge and energy transfers within the molecular edific

Multiple beam irradiation platform MIRRPLA: origin and evolution of organic matter in the solar system

International audience“Where do we come from?” is one of the important fascinating open questions of science andphilosophy. How did life emerge? What is the origin of organic matter in the universe? Couldlife also emerge on other worlds than our Earth? Complex organic molecules have indeed beenobserved in space (comets, meteorites, molecular clouds). In 2023, France launched theProgrammes et équipements prioritaires de recherche (PEPR) Origins (life and universe),through the program leader the National Centre for Scientific Research, to address thesequestions [1]. Understanding the origin of primitive organic matter during the formation andevolution of the solar system is fundamental because the contribution of extraterrestrial organicmatter via asteroids and comets is one of the possible sources of organic matter available toprimitive Earth [2]

Interaction of multiply charged ions with large free silver nanoparticles: Multielectron capture, fragmentation, and sputtering phenomena

International audienceWe report on the interaction of multiply charged ions at keV energies with free Ag nanoparticles with diameters of ∼6 nm (containing about 6600 Ag atoms). As the ionization energy increases only very slowly with the degree of ionization, multielectron capture processes are very likely to occur in peripheral collisions with large cluster sizes. However, due to the large particle size, the produced highly charged Ag nanoparticles are mostly stable. For projectile charge states below q=8 the geometrical cross section overcomes the cross section for peripheral electron transfer, and penetrating collisions become dominant. Therefore, these collisions can be described as ion collision with a nanosurface, where the distribution of small-size fragments with n<20 is due to sputtering events from the nanoparticle surface. This is in contrast to nanoparticles with a smaller diameter (<2 nm), where small fragments are produced by fission of multiply charged clusters