TIME-OF-FLIGHT PROFILE OF FULLERENE-LIKE FRAGMENT IONS IN FAST
$He^{2+}$-$C_{60}$ COLLISION

Yoichi Nakai, Tadashi Kambara, Akio Itoh$^{*}$, Hidetsugu
Tsuchida$^{\sharp}$, and Yasunori Yamazaki

The Institute of Physical and Chemical Research(RIKEN), Wako, Saitama
351-0198, JAPAN\\
Department of Nuclear Engineering, Kyoto University, Kyoto 606-01, JAPAN\\
Department of Physics, Nara Women's University, Nara 630-8506, JAPAN

We have measured the TOF spectra of product ions in 10MeV
$He^{2+}$-$C_{60}$ collision. We compared the experimental TOF peaks with
Monte Calro simulation for $C_{60}^{1+, 2+, 3+}{\rightarrow}C_{58}^{1+, 2+,
3+}+C_{2}$ with a certain lifetime. The asymmetric tails of longer TOF of
$C_{58}^{1+, 2+,3+}$ mainly come from delayed fragmentation with micro
second time scale observed in low-energy electron impact study.
(4 lines in manuscript)