DISSOCIATIVE CHARGE-TRANSFER REACTIONS OF N+(P-3), N2+((2)SIGMA(G)+), AR+(P-2(3/2,1/2)), AND KR+(P-2(3/2)) WITH SIF4 - THERMOCHEMISTRY OF SIF4+ AND SIF3+

Guided ion beam mass spectrometry is used to measure cross sections as a function of kinetic energy for interaction of N+(3P), N2+ (2SIGMA(g)+), Ar+(2P3/2,1/2), and Kr+(2P3/2) with SiF4. Energy dependences of these cross sections and previous results for the reaction of O+(4S) with SiF4 are analyzed to yield thermochemistry for SiF4+ and SiF3+. From the O+ and N+ systems, we find that the adiabatic ionization energy of SiF4 is 15.29 +/- 0.08 eV, consistent with less precise determinations in the literature. The heat of formation of SiF3+ at 0 K is determined as -29.3 +/- 0.6 kcal/mol and that for NF as 63.4 +/- 3.9 kcal/mol.