Time-of-Flight Measurements of Cesium-Iodide Cluster Ions

Abstract

Secondary ions ${\left[{\left(\mathrm{CsI}\right)}_n\mathrm{Cs}\right]}^{+}$, with $n$ up to ∼ 40, were produced by 8-keV ${\mathrm{Cs}}^{+}$ bombardment of CsI. The yield of clusters decreased smoothly with $n$ when observed in a time-of-flight mass spectrometer at effective times ∼ 0.2 μs after emission. Clusters with $n>\mathrm{}7\mathrm{}$ were found to be metastable, with lifetimes ≪ 100 μs. A large anomaly in the population of the disintegration products was measured at ∼ 70 μs after emission, $n=13\mathrm{}$ clusters being favored and $n=14\mathrm{} \mathrm{and} 15$ suppressed.