Formation of higher-order fullerene dianions in collisions with Na atoms P. Hvelplund, B. Liu, S. Brøndsted Nielsen and S. Tomita Eur. Phys. J. D, 43 1-3 (2007) 133-136 Published online: 24 May 2007 DOI: 10.1140/epjd/e2007-00072-2