Low Temperature Physics: 42, 156 (2016); https://doi.org/10.1063/1.4942580
Fizika Nizkikh Temperatur: Volume 42, Number 2 (February 2016), p. 207-211 ( to contents , go back )
A new approach to investigation of luminescence spectra of substrate-free icosahedral and crystalline nanoclusters of
Yu.S. Doronin, V.L. Vakula, G.V. Kamarchuk, A.A. Tkachenko, and V.N. Samovarov
B. Verkin Institute for Low Temperature Physics and Engineering National Academy of Sciences of Ukraine 47 Nauki Ave., Kharkiv, 61103, Ukraine
Received November 13, 2015
We propose a new approach to analysis of cathodoluminescence spectra of substrate-free nanoclusters of argon produced in a supersonic jet exhausting into a vacuum. It is employed to analyze the intensities of luminescence bands of the neutral and charged excimer complexes (Ar2)* and (Ar4+)* measured for clusters with an average size of 500 to 8900 atoms per cluster and diameters between 32 and 87 Å. The concentration of the jet substance condensed into clusters, which determines the values of the integrated band intensities, is shown to be proportional to the logarithm of the average cluster size. Analysis of the reduced intensities of the (Ar2)* and (Ar4+)* bands observed from crystalline clusters with an fcc structure allowed us to conclude that the emission of the neutral molecules (Ar2)* comes from within the whole volume of the cluster, while the charged complexes (Ar4+)* radiate from its near-surface layers. We found the cluster size range in which the jet is dominated by quasicrystalline clusters with an icosahedral structure and demonsrate that the transition from icosahedral to fcc clusters occurs when the average cluster size is N = (1000–1800) atoms per cluster.
PACS: 36.40.–c Atomic and molecular clusters;
Key words: argon nanocluster, cathodoluminescence spectrum, icosahedral structure, fcc structure.
Published online: December 23, 2015