7376. Investigation of the dependence of the secondary processes in channeling on the location of impurity atoms in the near surface layers of single crystals: P A Aleksandrov and L I Ognev, Nucl Instrum Meth Phys Res, B51, 1990, 273–277

Abstract

The sol–gel method was used to prepare two families of organic/inorganic hybrids incorporating europium triflate, classed as di-urethanesils and aminosils. A siliceous network to which short polyether chains are covalently bonded through urethane linkages, composes the di-urethanesil host. A siliceous network containing pendant amine terminated propyl chains, forms the aminosils. The xerogels were investigated by photoluminescence, particularly the local interaction between the Eu3+ ions and the host matrix. The Eu3+ local coordination was modelled in terms of a local-field perturbation representing the ion’s nearest ligands interaction potential. While for the aminosils the Eu3+ ions occupy one low-symmetry local site—crystal-field strength of ca. 760.5 cm−1 and 5D0 lifetime of 0.6–0.7 ms—two local Eu3+ environments with distinct point symmetry group, 5D0 lifetimes (ca. 0.2–0.3 and 1.4–1.8 ms, respectively) and covalent nature—crystal-field strengths of ca. 540 and 740–780 cm−1, respectively—were identified in the di-urethanesils.