TEMPERATURE AND CLUSTER SIZE DEPENDENCE STUDIES OF REACTIONS OF PROTONATED WATER CLUSTERS WITH ACETONITRILE

The temperature dependence of reactions of protonated water clusters H+ (H2O)n with acetonitrile CH3CN was studied in a fast-flow reactor over the temperature range of 300-130 K and for cluster sizes from n equals 1 to 22. The measured rate constants were found to agree well with the calculated values based on a parametrized trajectory method [T. Su and W. J. Chesnavich, J. Chem. Phys. 76, 5183 (1982)] over the entire range of the temperatures and cluster sizes studied. The rate constants measured in this work also agree very well with other reported values at room temperature. These results demonstrate that collisional rate constants for the type of the cluster-ion-molecules reactions studied here can be calculated accurately by the theoretical method at room as well as low temperatures. This conclusion not only has a direct bearing on other research fields, e.g., the modeling atmospheric ion chemistry at low temperatures, but also offers insight into the reaction dynamics of cluster-ion-molecule reactions as well.