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

Abstract

Secondary ions ${[{(\mathrm{CsI})}_{n}\mathrm{Cs}]}^{+}$, with $n$ up to \ensuremath{\sim} 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 \ensuremath{\sim} 0.2 \ensuremath{\mu}s after emission. Clusters with $n>7$ were found to be metastable, with lifetimes \ensuremath{\ll} 100 \ensuremath{\mu}s. A large anomaly in the population of the disintegration products was measured at \ensuremath{\sim} 70 \ensuremath{\mu}s after emission, $n=13$ clusters being favored and $n=14 \mathrm{and} 15$ suppressed.