Electron-induced fluorescence of carbon dioxide clusters. I. Free jet of condensing gas

In measurements in jets of condensing gases, problems arise in interpreting the results obtained with the use of electron-beam fluorescence diagnostics, in particular due to the possible contribution of clusters to the radiation from the jet. Data on the fluorescence are obtained by comparing the optical and x-ray emission excited by an electron beam with calculations of the amount of condensate. Studies are made on the fluorescence of CO 2 clusters excited by an electron beam in a free jet of the condensing carbon dioxide gas. It is found that the clusters radiate at wavelengths of the monomers extremely effectively per molecule, almost as much as the free molecules, and the dependence on size is quite weak. It is shown that with electron-impact excitation the emission of the clusters comes about as the result of the ejection of excited molecules from the cluster as the latter fragments. The results of this investigation of the fluorescence of CO 2 clusters lead to conclusions regarding the use of electron beam fluorescence diagnostics for measurements in free jets with CO 2 clusters.