title: Correlating structure with non-linear optical properties in xAs40Se60·(1-x)As40S60 glasses.
abstract: A series of xAs40Se60·(100 - x)As40S60 glasses, where x = 0, 25, 33, 50, 67, 75 and 100 mol% As40Se60, has been studied using neutron and X-ray total scattering, Raman spectroscopy and (77)Se MAS-NMR. The results are presented with measurements of non-linear refractive indices, n2, and densities. There is no evidence for the formation of homopolar bonds in these glasses, but neutron correlation functions suggest that there is a non-random distribution of sulfur and selenium atoms in sulfur-rich glasses. The average number of sulfur atoms at a distance of 3-4 Å from a selenium atom, nSeS, deviates from a linear variation with x in glasses containing <50 mol% As40Se60; n2 for these glasses also varies non-linearly with x. Importantly, a direct comparison of n2 and nSeS gives a linear correlation, suggesting that n2 may be related to the distribution of chalcogen atoms in the glasses.
authors: Faculty of Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. Emma.Barney@nottingham.ac.uk.
authors: Emma R
authors: ER
authors: Barney
authors: Nabil S
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authors: Abdel-Moneim
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authors: Towey
authors: Jeremy
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authors: David
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