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From Quantum Confinement in Carbon Nanotubes to a Harpoon-Type Electron Transfer in a Helium Droplet

AuthorsLara Castells, María Pilar de ; Hauser, Andreas W.; Mitrushchenkov, Alexander O.
Issue Date2-Oct-2017
CitationMOLIM Workshop on Intermolecular Interactions (2017)
AbstractHigh-surface areas and precisely tuned pores of carbon nanotubes make them relevant materials for applications such as in gas adsorption, selective separation of light isotopes, and nanoreactors for quasi one-dimensional confinement of metal nanoparticles. Understanding the role of quantum nuclear effects and intramolecular interactions in the motion of molecules in carbon nanotubes is deeply fundamental. Very recent experimental measurements at low temperatures (2-5 K) of Ohba [1] revealed that much more molecules of nitrogen than helium atoms absorb in small diameter (below 0.7 nm) carbon nanopores, despite of the larger kinetic diameter of the former. Using the helium density-functional formulation for a large 4He droplet containing a carbon nanotubes inside, we first show that the experiment can be understood by considering very large zero-point effects in the helium motion, which includes the formation of cavities with zero helium densities [2]. Second, we present an ad-hoc developed nuclear wave-function treatment to provide a detailed insight into the effects of quantum confinement for both N2 and 4He clusters in carbon nanotubes as a function of the tube diameter [3]. Third, we introduce a pairwise potential model [3] to describe the gas adsorption to carbon materials which relies on DFT-based symmetry-adapted perturbation theory [4]. Fourth, we propose a mixed approach combining nuclear density functional and wave-function treatments [3]. Preliminary results extending the treatment to deuterium molecular clusters in carbon nanotubes will be also presented [5]. As a second topic, we will present 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 [6,7]. The heliophobic Cs or Cs2 species are initially located at the droplet surface, while the heliophilic C60 molecule is fully immersed into the droplet. First, probabilities for the electron transfer in gas phase were calculated for reactants with velocities below the critical Landau velocity of 57 m/s to account for the superfluid helium environment. Next, reaction pathways were derived which 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 [8] showing a high possibility for the formation of a Cs2-C60 complex inside the droplet through a direct harpoon-type electron transfer involving the rotation of the molecule, but a negligible low reactivity for atomic Cs. [1] Ohba 2016 Sci. Rep.6 28992. [2] A. W. Hauser and M. P. de Lara-Castells 2016 J. Phys. Chem. Lett. 7 4929. [3] A. W. Hauser, A. O. Mitrushchenkov, and M. P. de Lara-Castells 2017 J. Phys. Chem. C 121 3807 [4] M. P. de Lara-Castells and A. O. Mitrushchenkov, 2015 J. Phys. Chem. A 119 11022 [5] M. P. de Lara-Castells, A. W. Hauser, A. O. Mitrushchenkov, and R. Fernández-Perea, 2017 Phys. Chem. Chem. Phys. (submitted). [6] M. P. de Lara-Castells, A. W. Hauser, and A. O. Mitrushchenkov 2017 J. Phys. Chem. Lett. 8 4284 [7] A. W. Hauser and M. P. de Lara-Castells 2017 Phys.Chem. Chem. Phys. 19 1342 [8] M. Renzler, M. Daxner, L. Kranabetter, A. Kaiser, A. W. Hauser, W. E. Ernst, A. Lindinger, R. Zillich, P. Scheider, and A. Ellis, 2016 J. Chem. Phys. 145 181101
DescriptionConferencia invitada. -- MOLIM Workshop on Intermolecular Interactions, Faculty of Chemistry, Santiago de Compostela, 2-4 October 2017. -- http://www.usc.es/en/congresos/molim
Appears in Collections:(CFMAC-IFF) Comunicaciones congresos
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