title: Stabilities of multiply charged dimers and clusters of fullerenes.
abstract: The authors find even-odd variations as functions of r (<or=7) for multiple ionization of van der Waals dimers in slow Xe(30+)+[C60]2([C60C70])-->...+[C60]2(r+)([C60C70](r+)) electron-transfer collisions. This even-odd behavior is in sharp contrast to the smooth one for fullerene monomers and may be related to even-odd effects in dimer ionization energies in agreement with results from an electrostatic model. The kinetic energy releases for dimer dissociations [predominantly yielding intact fullerenes [C60]2(r+)-->C60(r1+)+C60(r2+) in the same (r1=r2) or nearby (r1=r2+/-1) charge states] are found to be low in comparison with the corresponding model results indicating that internal excitations of the separating (intact) fullerenes are important. Experimental appearance sizes for the heavier clusters of fullerenes [C60]n(r+) (n>3 and r=2-5) compare well with predictions from a new nearest-neighbor model assuming that r unit charges in [C60]n(r+) are localized to r C60 molecules such that the Coulomb energy of the system is minimized. The system is then taken to be stable if (i) two (singly) charged C60 are not nearest neighbors and (ii) the r C60(+) molecules have binding energies to their neutral nearest neighbors which are larger than the repulsive energies for the (r-1) C60(+)-C60(+) pairs. Essential ingredients in the nearest-neighbor model are cluster geometries and the present results on dimer stabilities.
authors.affiliation: Physics Department, Stockholm University, AlbaNova University Center, SE-106 91 Stockholm, Sweden. henning@physto.se
authors.forename: Henning
authors.initials: H
authors.lastname: Zettergren
authors.forename: Henning T
authors.initials: HT
authors.lastname: Schmidt
authors.forename: Peter
authors.initials: P
authors.lastname: Reinhed
authors.forename: Henrik
authors.initials: H
authors.lastname: Cederquist
authors.forename: Jens
authors.initials: J
authors.lastname: Jensen
authors.forename: Preben
authors.initials: P
authors.lastname: Hvelplund
authors.forename: Shigeo
authors.initials: S
authors.lastname: Tomita
authors.forename: Bruno
authors.initials: B
authors.lastname: Manil
authors.forename: Jimmy
authors.initials: J
authors.lastname: Rangama
authors.forename: Bernd A
authors.initials: BA
authors.lastname: Huber