A new approach to studying the cathodoluminescence spectra of free quasicrystalline and crystalline inert-element clusters

• Published in: Low temperature physics (Woodbury, N.Y.) N.Y.), 2020-02, Vol.46 (2), p.145-154
• Main Authors: Vakula, V. L., Danylchenko, O. G., Doronin, Yu. S., Kamarchuk, G. V., Konotop, O. P., Samovarov, V. N., Tkachenko, A. A.
• Format: Article
• Language: English
• Subjects: Argon; Cathodoluminescence; Cluster analysis; Clustering; Crystal structure; Crystallinity; Diameters; Electron diffraction; Excimers; Exhausting; Icosahedral phase; Krypton; Luminescence; Rare gases; Spectra; Spectral bands; Xenon
• ISSN: 1063-777X; 1090-6517
• DOI: 10.1063/10.0000533

The paper proposes a new approach to the quantitative analysis of the cathodoluminescence spectra of free clusters of inert elements produced in a supersonic jet exhausting into a vacuum. This approach takes into account the level of substance clustering in the jet, and is used to analyze the luminescence band intensities of the neutral and charged (Rg2)* and (Rg4+)* excimer complexes measured for the nanoclusters of three inert gases (Rg = Ar, Kr, and Xe), with the average size ranging from 100 to 18000 atoms per cluster (diameters varying from 2 to 13 nm). The concentration of the clustered substance, which affects the absolute values of the integrated intensity of the spectral bands, is shown to be proportional to the logarithm of the average size of the clusters in the jet. Analysis of the normalized intensities allowed us to use our cathodoluminescence spectra to establish two ranges of average nanocluster size which, according to the electron diffraction studies, can be identified as those corresponding to the quasicrystalline icosahedral and crystalline fcc structures in clusters of argon, krypton, and xenon, as well as to find an intermediate area in which both structures coexist. It is shown that in fcc clusters the luminescence of the (Rg2)* neutral molecules comes from within the volume of the cluster, while the charged (Rg4+)* excimer complexes emit mostly from a subsurface layer.