OBSERVING UNIMOLECULAR DISSOCIATION OF METASTABLE IONS IN FT-ICR - A NOVEL APPLICATION OF THE CONTINUOUS EJECTION TECHNIQUE

The application of the continuous ejection technique to observe unimol ecular dissociation of metastable organometallic ions in a Fourier tra nsform ion cyclotron resonance (FT-ICR) mass spectrometer is demonstra ted. A radio-frequency ejection voltage is continuously applied at a f requency corresponding to the exact mass of a metastable adduct ion, [ MC6H6+] (M = Cr and Mn), formed in the reactions of Cr+ and Mn+ with C6H6. By monitoring the initial metal ion intensity as a function of i on ejection time, metastable ion lifetimes and unimolecular dissociati on rate constants are obtained, The bond dissociation energies D-0(Cr-C6H6)=1.75 +/- 0.1 eV and D-0(Mn+-C6H6) = 1.50 +/- 0.1 eV are derived from RRKM modeling and are in excellent agreement with other literatu re values.