Adsorption of helium on a charged propeller molecule: hexaphenylbenzene Siegfried Kollotzek, Florent Calvo, Serge Krasnokutski, Fabio Zappa, Paul Scheier and Olof Echt Eur. Phys. J. D, 75 11 (2021) 299 Published online: 29 November 2021 DOI: 10.1140/epjd/s10053-021-00301-6