Formation of fluorescent aggregates in Rhodamine 6G doped silica glasses

The photoluminescence properties of type I sol-gel synthesized Rhodamine 6G doped silica samples were investigated in the 1.5 x 10(-4)-1.5 x 10(-3) mol/l range of concentration by means of steady-state and time resolved photoluminescence measurements. The emission peak red shifts as the concentration increases. For a fixed concentration, the peak position also red shifts as the excitation wavelength decreases. The observed spectroscopic features, including excitation of photoluminescence and decay time, indicate the formation of fluorescent dimers. (c) 2007 Elsevier B.V. All rights reserved.