Selection of Publications in 2017

We have selected the following articles published in 2017:

1) The first selected paper of our group presents an ab-initio approach to study the quantum nuclear motion of molecular clusters in carbon nanotubes. More precisely, we study the quantum nuclear motion of N 4He atoms or N N2 molecules (N < 4) confined in carbon nanotubes using an ad hoc-developed nuclear wave function-based approach. Density functional theory (DFT)-based symmetry-adapted perturbation theory is used to derive parameters for a new pairwise potential model describing the gas adsorption to carbon materials. The predicted nuclear motion of He atoms inside a confining potential is directly compared to probability densities obtained by orbital-free He-DFT theory. The interaction of small clusters of adsorbates is also studied via a combination of both the discrete atomic and the continuous density approaches. Our results agree well with previouslyeported experimental and theoretical studies and provide new physical insights into the very different quantum confinement effects depending on the diameter of the carbon nanotubes and the impact of quantum phenomena on the gas storage capabilities at low temperatures.

The article includes an extensive supplementary information and a ACS SlideLive presentation.

This study has been developed within the framework of our collaboration with Andreas W. Hauser (Graz University of Technology) and Alexander O. Mitrushchenkov (Université Paris-Est).

Journal of Physical Chemistry C, 2017, 121, 3807-3821

http://doi.org/10.1021/acs.jpcc.6b12959

 

 

2) The second selected paper of our group presents an ab initio study of a long-range electron transfer or “harpoon”-type process from Cs and Cs2 to C60 in a superfluid helium droplet. The heliophobic Cs or Cs2 species are initially located at the droplet surface, while the heliophilic C60 molecule is fully immersed in the droplet. First, probabilities for the electron transfer in the gas phase are calculated for reactants with velocities below the critical Landau velocity of 57 m/s to account for the superfluid helium environment. Next, reaction pathways are derived that also include the repulsive contribution from the extrusion of helium upon the approach of the two reactants. Our results are in perfect agreement with recent experimental measurements of electron ionization mass spectroscopy [Renzler, M.; et al., J. Chem. Phys. 2016, 145, 181101], showing a high possibility for the formation of a Cs2−C60 complex inside of the droplet through a direct harpoon-type electron transfer involving the rotation of the molecule but a negligibly low reactivity for atomic Cs.

The article includes an extensive supplementary information and a ACS SlideLive presentation. It is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

This study has been developed within the framework of our collaboration with Andreas W. Hauser (Graz University of Technology) and Alexander O. Mitrushchenkov (Université Paris-Est).

Ab Initio Confirmation of a Harpoon-Type Electron Transfer in a Helium Droplet

Journal of Physical Chemistry Letters, 2017, 8 (17), 4284-4288

http://doi.org/10.102/acs.jpclett.7b01910

 

3) The third selected article of our group presents experiments and calculations of the deposition and aggregation of silver clusters embedded in helium droplets onto an amorphous carbon surface at room temperature. Calculations were also performed for deposition onto a graphene surface. They involve potentials for the interaction of carbon atoms with silver and helium atoms, provided by ab initio calculations. The numerical simulations were performed for few-nanometer-sized silver clusters including up to 5000 Ag atoms and He droplets with up to 105 4He atoms. The fluid nature of the 4He droplet is accounted for by the renormalization of the He− He interaction potential. The numerical results are consistent with deposition experiments with an average number of 3000 Ag atoms per 4He droplet and indicate that the aggregation of the silver clusters on the carbon surface is mediated by secondary droplet impacts. They also reveal nontrivial dynamics of the Ag clusters within the carrier droplet, showing a tendency to drift toward the droplet surface. These findings are of relevance in understanding the heterogeneous deposition patterns (large ramified islands) developed for very large droplets with an average  number of Ag atoms per droplet within the million range. Finally, the simulations of large (5000 atoms) Ag cluster deposition on graphene reveals strong superdiffusive behavior. In stark contrast, the diffusion is negligible on the amorphous carbon surface.

This study has been developed within the framework of our collaboration with Andrey Vilesov (University of Southern California), Martí Pi (University of Barcelona), and Alexander O. Mitrushchenkov (Université Paris-Est).

Ricardo Fernández-Perea, Luis F. Gómez, Carlos Cabrillo, Martí Pi, Alexander O. Mitrushchenkov, Andrey F. Vilesov*, and María Pilar de Lara-Castells*

Helium Droplet-Mediated Deposition and Aggregation of Nanoscale Silver Clusters on Carbon Surfaces

Journal of Physical Chemistry C, 2017, 121 (40), 22248–22257

http://doi.org/10.1021/acs.jpcc.7b08109

4) The fourth slected paper of our group presents nn ab initio study of quantum confinement of deuterium clusters in carbon nanotubes. First, density functional theory (DFT)-based symmetry-adapted perturbation theory is used to derive parameters for a pairwise potential model describing the adsorbate–nanotube interaction. Next, we analyze the quantum nuclear motion of N D2 molecules (N < 4) confined in carbon nanotubes using a highly accurate adsorbate-wave-function-based approach, and compare it with the motion of molecular hydrogen. We further apply an embedding approach and study zero-point energy effects on larger hexagonal and heptagonal structures of 7–8 D2 molecules. Our results show a preference for crystalline hexagonal close packing hcp of D2 molecules inside carbon nanotubes even at the cost of a reduced volumetric density within the cylindrical confinement. 

This study has been developed within the framework of our collaboration with Andreas W. Hauser (Graz University of Technology) and Alexander Mitrushchenkov (Université Paris-Est).

Physical Chemistry Chemical Physics, 2017, Advance Article

http://doi.org/10.1039/C7CP05869A