Impurity driven clustering in a gas aggregation source

Both gas phase Nan and Nan(NaOH)2 nanoparticle ensembles (n = 50–250) are produced in a gas aggregation source and studied by using laser-ionization time-of-flight mass spectrometry. Heterogeneous Nan(NaOH)2 clusters are shown to be produced by accretion of sodium atoms on nucleation centers initially formed by a chemical reaction between H2O and Na or Na2 molecules. Mass distributions are compared for Nan grown on an homogeneous nucleation center and for Nan(NaOH)2 developing on an heterogeneous seed in the same condensation source, allowing the comparison between homogeneous and heterogeneous clustering efficiency.