Optical study of oriented double-Se8-ring clusters and luminescent Se2− anions in LTA at extremely high selenium loading density

Recently, LTA-Se(1–8) samples with 1–8 Se atoms per cavity (simplified unit cell, large + sodalite cage) obtained via adsorption at the temperature of ∼450 °C were reported. It was shown that single Se8 or Se12 ring are formed in LTA cavities, Se8/Se12 concentration ratio decreasing an increase loading density. Contrary, present work, using vapour ∼550 °C, we succeeded encapsulation ∼17 (LTA-Se(17)) a significant manifesting double Se8-ring cluster formation most which is step towards crystal fabrication. According to our polarization/orientation Raman spectroscopic study LTA-Se(17) crystals, orientations and appeared be similar those previously investigated LTA-Se(1–8). Importantly, luminescent Se2− anions, oriented along 4-fold axes located cages, detected dependencies LTA-Se(17). Bright light emission maximum ∼1.56 eV vibronic structure observed 1.3–1.8 spectral range. We show anions experience compression slightly relaxing decrease producing anomalous band downshift. The weaker/stronger than sodalite/cancrinite, luminescence photon energy depending on its strength. High regularly arranged suggests considering as important novel light-emitting material.