Generation of (H2O2)N clusters on argon and ice nanoparticles

Hydrogen peroxide is a highly reactive and relatively unstable molecule, therefore pure (H2O2)N clusters are difficult to generate. In order to investigate the solvent effects on the H2O2 reactivity, experiments with H2O2 clusters are desirable. We have generated (H2O2)N clusters on free nanoparticles in molecular beams using a pickup technique. The individual H2O2 molecules were evaporated from the stable complex of urea with hydrogen peroxide (UHP) and they were picked up by ArM and (H2O)M nanoparticles in a molecular beam prepared by supersonic expansion. The clusters were probed by the time-of-flight mass spectrometry after electron ionization. The mass spectra showed that several H2O2 molecules could be deposited on both ArM and (H2O)M nanoparticles. On ArM, they coagulate and generate (H2O2)N clusters with N ≥ 20, while on ice nanoparticles the coagulation is inhibited on the timescale of our experiment (∼ 0.7 ms). The mass spectra suggest that there is no significant contamination of the (H2O2)N clusters with oxygen and water, which would be the products of H2O2 thermal decomposition. The proposed method represents a way of producing (H2O2)N clusters for future experiments.