Direct ejection of clusters from nonmetallic solids during laser vaporization

We have demonstrated that laser vaporization of nonmetallic solids can produce atomic or molecular clusters and cluster ions by direct ejection of fragments from the sample surface. The spectra of cluster ions ([MX${]}_{\mathit{n}}$ ${\mathit{M}}^{+}$ and [MX${]}_{\mathit{n}}$ ${\mathit{X}}^{\mathrm{-}}$, n=1–40) formed by vaporizing mixed alkali-halide powder samples include virtually no alloyed species, indicating that the observed clusters do not grow from molecular vapor but are instead laser sputtered from the solid in a nonthermal shattering process. In carbon, large clusters result from partial evaporation of ultrafine particles on the sample.