Group Metting on-line (23rd March, 2021)
Attendants: Marta Hernández, Tomas González, Massimiliano Bartolomei, José Campos, Lukas Tiefenthaler, Florent Calvo, Nadine Halbserstad, Elizabeth Gruber, Paul Scheier, Siegfried Kollatzek, Eva María Zunzunegui.
University of Innsbruck (19th-24th September, 2021)
José Campos Martínez
Marta I. Hernández
CNRS- University of Toulouse (30th November, 4th December, 2021)
Marta I. Hernández
Marta I. Hernández
“Microscopic processes for hydrogen chemisorbed on graphene: permeation and recombination”.
Hydrogenated graphene is of great interest in several different fields such as hydrogen technologies, astrochemistry, nuclear fusion, electronics and magnetism. Using large molecular prototypes of graphene, we have carried out density functional theory computations to study in detail two processes occurring in this system, namely, the permeation or flipping of chemisorbed hydrogen atoms through graphene and the recombination of these atoms (desorption leading to the formation of hydrogen molecules), which can be regarded as the subsequent step after permeation. Firstly, we will present a new mechanism for the flipping of chemisorbed hydrogen atoms1 or protons2 through a graphene layer (see figure), where we have found that the activation energies involved are of the order of recent experimental findings 3,4. In addition, we will show preliminary results on reaction paths and rate coefficients for the recombination of hydrogen and deuterium, which exhibit large isotopic substitution effects (due to zero-point energy and tunneling) in qualitative agreement with thermal desorption measurements5,6. We believe that these studies will help to rationalize the experimental results as well as to provide some clues about properties of hydrogenated graphene.
 M. Bartolomei, M. I. Hernández, J. Campos-Martínez, R. Hernández-Lamoneda, G. Giorgi, “Permeation of chemisorbed hydrogen through graphene: a flipping mechanism elucidated”, Carbon 2021, 178, 718
 M. Bartolomei, M. I. Hernández, J. Campos-Martínez, R. Hernández-Lamoneda, “Graphene multi-protonation: A cooperative mechanism for proton permeation”, Carbon 2019, 144, 724.
 S. Hu et al, “Proton transport through one-atom-thick crystals”, Nature 2014, 516, 227.
 P. Z. Sun et al, “Limits on gas impermeability of graphene”, Nature 2020, 579, 229
 T. Zecho et al, “Adsorption of hydrogen and deuterium atoms on the (0001) graphite surface”, J. Chem. Phys. 117, 8486 (2002)
 L. Hornekaer et al, “Metastable structures and recombination pathways for atomic hydrogen on the graphite (0001) surface”, Phys. Rev. Lett. 96, 156104 (2006)
Theory Group Meeting Talks:
“Ab initio results for H2 molecules adsorbed on Naphthalene doped with Na atoms”
“Transmission of hydrogen isotopes through a graphdiyne layer”
Madrid (February, 13th)
Siegfried Kollatzek (from University of Innsbruck, Austria).
Seminar at IFF
Sala de conferencias, C/ Serrano 121
Miercoles 16 de marzo de 2022 a las 12:00
HOW TO DOPE HIGHLY CHARGED HELIUM NANO DROPLETS
Institute for Ion Physics and Applied Physics,
University of Innsbruck, Austria
Building on our recent report  on the production of stable, highly charged droplets of superfluid helium, a new experimental method  was designed to investigate chemical and physical cluster processes in the sub-kelvin environment with a high ion yield. Properties of clusters often depend critically on the exact number of atomic or molecular building blocks, however, most methods of cluster formation lead to a broad size distribution and cluster intensity anomalies often designated as magic numbers. Here we present a novel approach of breeding narrowly size selected clusters via pickup of dopants into multiply-charged helium nanodroplets (A). We also demonstrate a method of softly ionizing dopant molecules by proton transfer , while largely preventing fragmentation, even for notoriously delicate molecules (B). Finally, recent measurements indicate promising results while studying the influence of sodium atoms doped onto PAH’s on their ability to reversible attach H2 molecules (C).
 F. Laimer et al Phys. Rev. Lett. 123, 165301 (2019)
 L. Tiefenthaler et al. Rev. Sci. Instrum. 91, 033315 (2020)
 L. Tiefenthaler and S. Kollotzek et al. Phys. Chem. Chem. Phys. 22, 28165-28172 (2020)
links of interest