The energy dependence of the forward and backward rate coefficients for clustering reactions of Li+ ions with Ar, Kr, and Xe

Abstract

The energy dependence of the clustering reactions of Li+ ions with Ar, Kr, and Xe has been measured in the pressure range 2-4 Torr using a drift tube without mass spectrometer. The energy (center of mass) of the Li+ ions was varied over the range 41-67 meV in Ar, 43-129 meV in Kr, and 48-207 meV in Xe. The energy of the cluster ions was varied over the range 40-44 meV in Ar, 40-48 meV in Kr, and 40-43 meV in Xe. All the gases were maintained at room temperture. It is found that the forward rate coefficients are inversely proportional to the ion energy in all cases. The backward rate coefficients increase rapidly with increasing cluster ion energy. Arrhenius plots of the backward rate coefficients gives the activation energy as 0.34 eV in Ar, 0.45 eV in Kr, and 0.49 eV in Xe.

The Reaction Rate Coefficient for the Clustering of He to Li + at Low Centre of Mass Energies

“…energies of ::::;50 meV. The present values indicate that for Li+ clustering with He atoms at room temperature,the reaction rate coefficient at ::::;50 meV will be <5xlO-33 cm 6 s-1 • This may be compared with values of 1·8xlO-31 cm 6 s-1 (for Ar), 2.5xlO-31 cm 6 s-1 (for Kr) and 4xlO-31 cm 6 s-1 (for Xe) obtained by Takebe et al (1982).…”

“…energies using the 'tsureko' method of Takebe et al (1982). The present study demonstrates why Li + .…”

“…(1) k was measured using the 'tsureko' method of Takebe et al (1982). This method is based on a simple analysis of time-of flight spectra obtained when parent and product ion species are present and is particularly useful in the measurement of very small values of k. The method does not require ions to be sampled from the drift tube, but in the present work checks were made using a quadrupole mass spectrometer and ion sampling to determine the identities of the ions present.…”