Dissociative Recombination of OPCl(+) and OPCl(2+): Pushing the Upper Mass Limit at CRYRING

The dissociative recombination of OPCI(+) and OPCI(2)(+) has been studied at the storage ring CRYRING. The rate constants as a function of electron temperature have been derived to be 7.63 x 10(-7)(T(e)/300)(-0.89) and > 1/2 x 10-6 (T(e)/300)(1.22) cm(3) s(-1). respectively. The lower limit quoted for the latter rate constant reflects the experimental inability to detect all of the reaction products. The branching fractions from the reaction have been measured for OPC1+ at approx. 0 eV interaction energy and are determined to be N(O+P+C1)=( 16 7), N(O+PC1)=( 16 3)% and N(OP+Cl)=(68 5)%. These values have been obtained assuming that the rearrangement channel forming P+CIO is negligible, and ah initio calculations using GAUSSIAN03 are presented for the ion structures and energetic to support such an assumption. Finally, the limitations to using heavy ion storage rings such as CRYRING for studies into the dissociative recombination of large singly charged molecular ions are discussed.
Published in the Journal of Chemical Physics, v128 n134308-1 through 134308-7, 2008. Prepared in collaboration with Boston College, Chestnut Hill, MA, under contract no. FA8718-04-C-0006, and with Stockholm University, Stockholm, Sweden.