Radial breathing modes in silver selenide quantum dots

Silver selenide (Ag₂Se) quantum dots obtained in synthetic zeolite F9 through ion exchange are reported in this work. A hydrothermal reaction was conducted between the zeolite-Ag⁺ system with Na₂SeSO₃. Quantum dots smaller than 10 nm were measured by Transmission Electron Microscopy (TEM). The particles have a cubic structure with a phase lm-m (229). A shoulder centered at 150 cm^-1 was experimentally detected after the synthesis of quantum dots by Raman Spectroscopy. The Density Functional Theory (DFT) was employed to determine a possible allocation to the Raman band detected. The LSDA (Local Spin Density Approximation) approximation levels and B3LYP (Becke's three-parameter Exchange functional and the gradient corrected functional of Lee, Yang and Puar) were employed in combination with the basis set LANL2DZ (Los Alamos National Laboratory 2-double-ζ) to study the structural and vibrational properties in minimum energy clusters (AgSe)_n. Radial Breathing Modes were detected between 150 and 252 cm^-1 for these levels of approximation.