CHEMISTRY AND KINETICS OF PRIMARY REACTIONS OF TI+ WITH H2O, NH3, CH3OH, C2H4, AND C3H6 AT THERMAL ENERGIES

The primary reactions of Ti+ with H2O, NH3, CH3OH, C2H4, and C3H6 were studied in the gas phase using a newly built SIDT-LV (selected ion drift tube with laser vaporization source) operated at thermal energies. The metal ion is produced by a standard pulsed laser vaporization source. After selection by a quadrupole mass spectrometer, Ti+ is injected into a drift tube reactor with 0.7 Torr of He as buffer gas, whereupon the ion reacts with a selected reactant introduced therein. Ions exiting the tube are analyzed and detected using a second quadrupole mass spectrometer affixed with a channeltron electron multiplier detector. For each of the primary reactions, we have measured the reaction product distribution and the bimolecular rate constants. All the reactions studied in this work are observed to proceed via bimolecular reaction mechanisms. Ti+ displays a very high reactivity toward breaking C-H, O-H, N-H, and C-O bonds in these reactants. A dehydrogenation reaction is found to be the only channel in all of these reactions except ones with methanol. The order of the dehydrogenation rate constants is found to be the same as the inverse order of the bonding strength of X-H bonds, and the results can be explained on the basis of dehydrogenation mechanisms. In the case of methanol, Ti+ is also able to break C-H and O-H bonds to form other products, although TiOH+ is the dominant product formed from breaking the C-O bond.