11–15 Jun 2018
Geological Museum, University of Copenhagen
Europe/Copenhagen timezone

Superhydrogenation of PAHs through interaction with hydrogenated grain surfaces

14 Jun 2018, 12:20
7m
Main Auditorium (Geological Museum, University of Copenhagen)

Main Auditorium

Geological Museum, University of Copenhagen

Øster Voldgade 5 - 7, 1350 København K, Denmark
Board: 173
Poster What is dust? Poster Presentations

Speaker

John Thrower (Department of Physics & Astronomy, Aarhus University, Denmark)

Description

The formation of molecular hydrogen, $\mathrm{H_2}$, in the ISM is thought to primarily occur on dust grain surfaces. This process has been investigated extensively through a variety of experimental and theoretical approaches for several different model grain surfaces. More recently it has been suggested that PAHs, representing the molecular limit of the carbonaceous grain population, can act as catalysts for $\mathrm{H_2}$ formation through the generation of superhydrogenated PAH, or HPAH species (Rauls & Hornekær 2008). In addition to interaction with gas-phase hydrogen atoms (Thrower et al. 2012), our laboratory measurements have shown that adsorption of PAHs on hydrogenated graphitic surfaces can also lead to the formation of HPAHs through the pick-up of adsorbed H-atoms that are bound to the graphite surface (Thrower et al. 2014). Whilst mass spectrometry provides evidence for the formation of HPAHs through this mechanism, the exact hydrogen adsorption sites occupied remains unclear. Scanning tunneling microscopy (STM) provides us with the ability to probe the adsorption and hydrogenation of PAHs at the micropscopic level. Using coronene $\mathrm{C_{24}H_{12}}$ as a prototypical PAH molecule, we show that a variety of hydrogenation structures are formed following adsorption on a hydrogenated HOPG surface. We also demonstrate how the surface temperature affects the hydrogenation process, which depends on the ability of the adsorbed coronene to scan the surface in order to pick up the adsorbed hydrogen atoms.

References

Rauls, E. & Hornekær, L., 2008, Astrophys. J., 679, 531.
Thrower, J. D., Jørgensen, B., Friis, E. E., Baouche S., Mennella, V., Andersen, M., Hammer, B., & Hornekær, L., 2012, Astrophys. J., 752, 3.
Thrower, J. D., Friis, E. E., Skov, A. L., Jørgensen, B. & Hornekær, L., 2014, Phys. Chem. Chem. Phys., 16 3381.

Consider for a poster? Yes

Primary author

John Thrower (Department of Physics & Astronomy, Aarhus University, Denmark)

Co-authors

Jakob Jørgensen (Department of Physics & Astronomy and iNANO, Aarhus University, Denmark) Anders Skov (Department of Physics & Astronomy, Aarhus University, Denmark) Frederik Simonsen (Department of Physics & Astronomy, Aarhus University, Denmark) Liv Hornekær (Department of Physics & Astronomy and iNANO, Aarhus University, Denmark)

Presentation materials