Formation of Ca_O Clusters and Their Protonation and Hydration in direct Laser Vaporization

摘要

Calcium oxide clusters produced in the direct laser vaporization of different solid samples CaO, Ca(OH)_2 and CaCO_3 have been investigated by a time-of-flight mass spectrometer. Besides [Ca(CaO_n)]~+ and [(CaO)_n]~+ clusters, considerable protonated clusters [H(CaO)_n]~+ and hydrated clusters [H(CaO)_n(H_2O)_m]~+ have also been found in the TOF mass spectra. The characteristic of the abundance distribution of the clusters shows that the formation process of calcium oxide clusters should proceed along the growth course of the rock salt structure, which is further supported by the reactivity of [H(CaO)_n]~+ clusters with H_2O produced in the direct laser vaporization.