Mass-analyzed ion kinetic energy spectroscopy (MIKES) has been used to study the unimolecular and collision induced dissociation (CID) of C~6F~6^+ ions in collision with Ar and He at 3kV ion energy. The results indicated that C-F bond cleavage occurred via two channels. The corresponding energy shifts were 0eV (channel 1) and +9.8eV (channel 2) with Ar as collision gas, and 0eV (channel 1) and -17eV (channel 2) with He as collision gas. It also showed that C~6F~6^+ produced in the ion source was in a long-lived excited state of 17eV above the ground state. CID/Ar triggers its dissociation and releases the excess energy as kinetic energy or transfers the excess energy into internal energy.

Key words: UNIMOLECULAR REACTION, DECOMPOSITION REACTION, METASTABLE STATES, HELIUM, ARGON