Chemiluminescent Ba + N2O reaction in molecular clusters of CH4 and mixed ArCH4 clusters

We report measurements of visible chemiluminescence from a molecular cluster environment. Chemiluminescence spectra of the Ba + N2O reaction on pure CH4 clusters and on Ar clusters with a small fraction of CH4 have been measured and compared. As in the case of pure Ar clusters, there is a spectral contribution from rovibrationally ‘hot’ BaO∗, which is ejected immediately after the reaction, and a contribution from ‘cold’ solvated BaO∗. When using pure CH4 clusters the vibrational structure of the latter is washed out and a considerable blue-shift observed. From mixed ArCH4 clusters a superposition of pure cluster spectra is observed, and the blue-shift of the component influenced by CH4 is smaller than on pure CH4 clusters. This is interpreted by the formation of a still-luminescent BaO∗CH4 complex solvated on the Ar cluster.