Er. Lovejoy et Rr. Wilson, KINETIC-STUDIES OF NEGATIVE-ION REACTIONS IN A QUADRUPOLE ION-TRAP - ABSOLUTE RATE COEFFICIENTS AND ION ENERGIES, The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 102(13), 1998, pp. 2309-2315
A new apparatus consisting of an ion-molecule reactor coupled to a qua
drupole ion trap is described. The kinetics and products of the rapid
reactions of SF6- with SO2, HNO3, and HCl in the ion trap are reported
. There is excellent agreement between the ion trap rate coefficients
and yields, and flowing afterglow results. Rate coefficients for react
ions of products of the SF6- reactions are also reported. Measurements
of the equilibrium constant for the reaction NO3-. HNO3+HNO3 reversib
le arrow NO3-.(HNO3)(2) in the ion trap provide a very sensitive measu
re of the energy of the trapped ions. These measurements indicate that
the effective temperature of the trapped NO3-.(HNO3)(2) ion is 320 +/
- 30 K for an ion trap at 298 K (1-2 mTorr He, q(z) = 0.074). The pres
ence of 0.2 mTorr N-2 buffer gas increases the internal temperature of
the trapped ions by about 10 K. The internal temperature is also a we
ak function of the trapping potential, increasing by about 10 K over t
he range 0.074 < q(z) < 0.286.