Periodic Reporting for period 3 - QUANTUMGRAIN (Quantum Chemistry on Interstellar Grains)
Période du rapport: 2023-09-01 au 2025-02-28
We live in a molecular Universe, where we can find from the simplest molecule, H2, up to complex compounds of biological relevance like amino acids. The different steps leading to the formation of a planetary system like the solar one (i.e. from the formation of the star to the formation of the planets) is associated with a chemical evolution, in which at each step more complex molecules are formed. This chemical evolution is fundamental to know our astrochemical roots because it is ultimately connected with the origin of life.
The matter of space is mostly in the gas phase but the chemistry of space cannot be explained only by reactions taking place in the state. Besides, interstellar grains, minute solid particles ubiquitously present in several cosmic environments, play a key role as they provide the surfaces where chemical reactions occur more efficiently.
Traditionally, the interstellar grain chemistry has been investigated by astronomical observations, complemented by numerical models and laboratory experiments. However, this interdisciplinary approach presents some limitations, converging in a lack of atomic-scale information, which is fundamental to fully understand the chemistry occurring on the surfaces of interstellar grains. Because of that, the interstellar grain chemistry is a controversial issue that has baffled astrochemists for decades and its possibly crucial role in the existing chemical diversity and complexity is not well known. Fundamental questions such as “what are the reactions requiring the presence of grains and why?” and “what is the actual role of the grains ion these reactions?” are still unanswered.
The QUANTUMGRAIN (Quantum Chemistry on Interstellar Grains) project has the ambitious ultimate goal to unveil the grain surface chemistry by providing this missing atomic-scale information. This is obtained by state-of-the-art simulations based on quantum mechanical computations. The simulations will provide unique molecular pictures of the different elementary steps involved in the interstellar surface reactions as well unprecedented, quantitative data, essential to disclose the interstellar grain surface chemistry.
To fulfil this overall objective, the project is organized in three Work Packages (WPs), whose specific objectives are:
1) Characterise the detailed atomistic structures of different interstellar grains
2) Explore and characterise at a molecular level different on-grain surface reactions believed to occur during the Solar-type systems birth
3) Assess the actual role played by the grains in these reactions
The matter of space is mostly in the gas phase but the chemistry of space cannot be explained only by reactions taking place in the state. Besides, interstellar grains, minute solid particles ubiquitously present in several cosmic environments, play a key role as they provide the surfaces where chemical reactions occur more efficiently.
Traditionally, the interstellar grain chemistry has been investigated by astronomical observations, complemented by numerical models and laboratory experiments. However, this interdisciplinary approach presents some limitations, converging in a lack of atomic-scale information, which is fundamental to fully understand the chemistry occurring on the surfaces of interstellar grains. Because of that, the interstellar grain chemistry is a controversial issue that has baffled astrochemists for decades and its possibly crucial role in the existing chemical diversity and complexity is not well known. Fundamental questions such as “what are the reactions requiring the presence of grains and why?” and “what is the actual role of the grains ion these reactions?” are still unanswered.
The QUANTUMGRAIN (Quantum Chemistry on Interstellar Grains) project has the ambitious ultimate goal to unveil the grain surface chemistry by providing this missing atomic-scale information. This is obtained by state-of-the-art simulations based on quantum mechanical computations. The simulations will provide unique molecular pictures of the different elementary steps involved in the interstellar surface reactions as well unprecedented, quantitative data, essential to disclose the interstellar grain surface chemistry.
To fulfil this overall objective, the project is organized in three Work Packages (WPs), whose specific objectives are:
1) Characterise the detailed atomistic structures of different interstellar grains
2) Explore and characterise at a molecular level different on-grain surface reactions believed to occur during the Solar-type systems birth
3) Assess the actual role played by the grains in these reactions
The project is being developed by the participation of (a total, recruited at different stages) 9 PhD students, 5 postdocs and 1 technician. Three PhD theses have been sucessfully defended. In the following, the main work done is summarized.
We atomistically modelled in a realistic manner different interstellar grain surfaces: (i) those constituting the ice mantles, like pure water ice, pure CO ice and water:CO mixtures; (ii) refractory materials present in interstellar, cometary and meteoritic grains, like silicates, silica with metals, and iron sulphides. Dedicated electronic microscopy and nanoindentation measurements have been performed on meteoritic samples to determine their structure, composition and mechanical properties.
Atomistic simulations of the adsorption of a wide set of astrochemically-relevant species (O-, N- and S-containing compounds, and interstellar complex organic molecules, iCOMs) on icy surfaces and silicates have been performed. Unprecedented, accurate binding energies have been obtained, which are crucial in numerical models to explain the chemistry present in space.
Different chemical reactions occurring on the grains have been simulated: (i) formation of simple interstellar species (e.g. H2O, NH3, CH3OH), (ii) formation of organic compounds (e.g. iCOMs, hydrocarbons and alcohols), and (iii) formation of biomolecules (e.g. sugars, amino acids and nucleobases).
Simulations serve to determine the capability of interstellar water ices to act as third bodies, in which they absorb the energy released by the reactions, hence stabilizing the formed products. This has been the case for the formation of NH3 and iCOMs, where moreover, the energy dissipation mechanisms were deciphered.
Results provide deeper insights on the roles played by the grains in the interstellar chemistry. In some cases, grains accelerate the reactions (they act as chemical catalysts) by providing alternative less energetic synthetic paths. In others, grains retain the reactants on the surfaces allowing their encountering. For icy grains, a component of the ice is a reactant itself (grains act as reactant suppliers). Finally, for coupling reactions, grains act as efficient third bodies.
Results are being published in scientific articles in top-ranked journals and presented in different international congresses, mostly in the form of oral presentations but also posters. Research group activities are announced in our website (https://www.quantumgrain.eu(s’ouvre dans une nouvelle fenêtre)) and X account (@QuantumGrain), where we also disseminate our outreach activities, (e.g. popular science articles, blog posts and podcasts, https://www.quantumgrain.eu/outreach(s’ouvre dans une nouvelle fenêtre)).
We atomistically modelled in a realistic manner different interstellar grain surfaces: (i) those constituting the ice mantles, like pure water ice, pure CO ice and water:CO mixtures; (ii) refractory materials present in interstellar, cometary and meteoritic grains, like silicates, silica with metals, and iron sulphides. Dedicated electronic microscopy and nanoindentation measurements have been performed on meteoritic samples to determine their structure, composition and mechanical properties.
Atomistic simulations of the adsorption of a wide set of astrochemically-relevant species (O-, N- and S-containing compounds, and interstellar complex organic molecules, iCOMs) on icy surfaces and silicates have been performed. Unprecedented, accurate binding energies have been obtained, which are crucial in numerical models to explain the chemistry present in space.
Different chemical reactions occurring on the grains have been simulated: (i) formation of simple interstellar species (e.g. H2O, NH3, CH3OH), (ii) formation of organic compounds (e.g. iCOMs, hydrocarbons and alcohols), and (iii) formation of biomolecules (e.g. sugars, amino acids and nucleobases).
Simulations serve to determine the capability of interstellar water ices to act as third bodies, in which they absorb the energy released by the reactions, hence stabilizing the formed products. This has been the case for the formation of NH3 and iCOMs, where moreover, the energy dissipation mechanisms were deciphered.
Results provide deeper insights on the roles played by the grains in the interstellar chemistry. In some cases, grains accelerate the reactions (they act as chemical catalysts) by providing alternative less energetic synthetic paths. In others, grains retain the reactants on the surfaces allowing their encountering. For icy grains, a component of the ice is a reactant itself (grains act as reactant suppliers). Finally, for coupling reactions, grains act as efficient third bodies.
Results are being published in scientific articles in top-ranked journals and presented in different international congresses, mostly in the form of oral presentations but also posters. Research group activities are announced in our website (https://www.quantumgrain.eu(s’ouvre dans une nouvelle fenêtre)) and X account (@QuantumGrain), where we also disseminate our outreach activities, (e.g. popular science articles, blog posts and podcasts, https://www.quantumgrain.eu/outreach(s’ouvre dans une nouvelle fenêtre)).
QUANTUMGRAIN is a quantum chemistry-based project, in which computational simulations is the main mean to fulfil its main objective (and solve a major problem in Astrochemistry): to unveil interstellar grains in the chemical enrichment of a nascent Solar-type planetary system. The project consists of non-oriented fundamental research. Thus, its main aim is to further advance knowledge to make it available to society. Here, the new knowledge will rely on Astrocatalysis as an enhancer on the formation of interstellar compounds, thereby improving models explaining, ultimately, our astrochemical origins.
By reaching this target, we will also be capable to solve other related important issues:
i) to know the actual role of the interstellar grains in relevant surface reactions contributing to the molecular content present in space
ii) to have complete, unique molecular descriptions (i.e. the missing atomic-scale information) of the studied processes, which will be very used as accurate input parameters in the numerical models
iii) to determine the contribution of the interstellar grain chemistry in the overall chemistry of the Universe, hence helping to solve the challenging “cosmic chemical evolution” jigsaw puzzle.
The project will also contribute to the excellence, dynamism, and creativity, strengthening the European scientific research by providing excellent science and boosting quantum chemistry applied to space science. Space science represents an important inspirational tool for exciting and motivating young people and encouraging them to choose scientific careers. Space is also a domain that easily captures the interest of students towards education paths in the fields of science and technology. Huge investments are currently dedicated to observational ground/space borne instruments, also in Europe. It is a well-known fact that human activity linked to space exploration, detection of cosmic prebiotic molecules, search for propitious conditions for the emergence of life in exoplanets, etc., are all milestones in our attempt to clarify how life has emerged and how widespread is in the Universe.
By reaching this target, we will also be capable to solve other related important issues:
i) to know the actual role of the interstellar grains in relevant surface reactions contributing to the molecular content present in space
ii) to have complete, unique molecular descriptions (i.e. the missing atomic-scale information) of the studied processes, which will be very used as accurate input parameters in the numerical models
iii) to determine the contribution of the interstellar grain chemistry in the overall chemistry of the Universe, hence helping to solve the challenging “cosmic chemical evolution” jigsaw puzzle.
The project will also contribute to the excellence, dynamism, and creativity, strengthening the European scientific research by providing excellent science and boosting quantum chemistry applied to space science. Space science represents an important inspirational tool for exciting and motivating young people and encouraging them to choose scientific careers. Space is also a domain that easily captures the interest of students towards education paths in the fields of science and technology. Huge investments are currently dedicated to observational ground/space borne instruments, also in Europe. It is a well-known fact that human activity linked to space exploration, detection of cosmic prebiotic molecules, search for propitious conditions for the emergence of life in exoplanets, etc., are all milestones in our attempt to clarify how life has emerged and how widespread is in the Universe.