The interaction between interstellar molecules and dust grains is a source for enhancing complexity in the cosmos. Surfaces act as places for compounds to adsorb, encounter each other and further react to form new chemical species. The catalytic role of the surface of interstellar dust grains can lower the energy barriers for certain reaction paths and promote reactions which are forbidden in gas phase. Samples collected from meteorites show that interstellar dust grains usually contain crystallites presenting low index surface at their interfaces. Such surfaces can be modeled in the laboratory using a surface science approach. In our group, we take advantage on the instrumentation and know-how to simulate reactions which are of interest in astronomical conditions. In particular we are interested in the interplay between molecular hydrogen, polyciclic aromatic hydrocarbons (PAHs) and silicon carbide (SiC) surfaces.
In addition, aromatic molecules on surfaces are a playground to study their luminescence and the energy conversion routes between charges and photons on the single molecule level. For this purpose we combine atomic-scale scanning tunneling microscopy (STM) with STM-induced luminescence (STML) and optical emission spectroscopy (OES). Light can be easily detected from nanoscale systems, which permits to characterize dynamical processes in regimes that are not readily accessible by electronic means. By studying the environmentally-induced spectral modifications we strive at identifying new chemical species in astronomical observations. Our approach links the atomic structure and light emission properties of individual quantum systems at surfaces in order to characterize photochemical and photophysical rutes relevant in the circum- and inter- stellar media.
- Merino P., Švec M., Martínez J.I., Jelinek P., Lacovig P., Dalmiglio M., Lizzit S., Soukiassian P., Cernicharo J., Martín-Gago J.A. Graphene etching on SiC grains as a path to interstellar polycyclic aromatic hydrocarbons formation. Nature Communications, 5, 3054 (2014).
- Švec M., Merino P., Dappe, González C., Abad E., Jelinek P., J., Martín-Gago J.A. van der Waals interactions mediating the cohesion of fullerenes on graphene. Phys. Rev. B: Rapid Comm, 86, 121407 (2012).
- Merino P., Švec M., Martínez J.I., Mutombo P., González C., Martín-Gago J.A., de Andrés P.L, Jelinek P. Ortho and para hydrogen dimers on G/SiC (0001): combined STM and DFT study. Langmuir, 31, 233-239 (2014).
- Doležal J., Merino P., Redondo J., Ondič L., Cahlík A., Švec M. Charge carrier injection electroluminescence with CO-functionalized tips on single molecular emitters. Nano Letters, 19, 8605-8611 (2019).
- Martínez L.†, Santoro G.†, Merino P.†, Accolla M., Lauwaet K., Sobrado J., Sabbah H., Pelaez R.J, Herrero V.J., Tanarro I., Agúndez M., Martín-Jimenez A., Otero R., Ellis G.J., Joblin C., Cernicharo J., Martín-Gago J.A. Prevalence of non-aromatic carbonaceous molecules in the inner regions of circumstellar envelopes. Nature Astronomy, 4, 97-105, (2020)