Adsorption of helium on a charged propeller molecule: Hexaphenylbenzene

Siegfried Kollotzek (1) , Florent Calvo (2) , Serge Krasnokutski (3) , Fabio Zappa (1) , Paul Scheier (1) , Olof Echt (1, 4)

1 Universität Innsbruck [Innsbruck]
2 LIPhy - Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères]
3 Friedrich-Schiller-Universität = Friedrich Schiller University Jena [Jena, Germany]
4 UNH - University of New Hampshire

Physisorption on planar or curved graphitic surfaces or aromatic rings has been investigated by various research groups, but in these studies the substrate is usually strictly rigid. Here we report a combined experimental and theoretical study of helium adsorption on cationic hexaphenylbenzene (HPB), a propeller-shaped molecule. The orientation of its propeller blades is known to be sensitive to the environment, with substantial differences between the molecule in the gas phase and in the crystalline solid. Mass spectra of He n HPB + , synthesized in helium nanodroplets, indicate enhanced stability for ions containing n = 2, 4, 14, 28, 42, 44, or 46 helium atoms. Path-integral molecular dynamics simulations reveal a significant dependence of the dissociation energy on the details of the HPB geometry. Good agreement between the experimental data and calculated dissociation energies are obtained provided that the symmetry of HPB + is reduced from D 6 to D 2 , such a lower symmetry being suggested from quantum chemical calculations as arising upon electron removal.

Domaines: Chimie théorique et/ou physique

Siegfried Kollotzek, Florent Calvo, Serge Krasnokutski, Fabio Zappa, Paul Scheier, et al.. Adsorption of helium on a charged propeller molecule: Hexaphenylbenzene. The European Physical Journal D : Atomic, molecular, optical and plasma physics, 2021, 75 (11), pp.299. ⟨10.1140/epjd/s10053-021-00301-6⟩. ⟨hal-03854383⟩