ABSOLUTE THERMAL LENS METHOD TO DETERMINE FLUORESCENCE QUANTUM EFFICIENCY AND CONCENTRATION QUENCHING OF SOLIDS

An absolute thermal lens method to determine fluorescence quantum effi ciency and concentration quenching of solids is described in this work . The quantum efficiency of low silica calcium aluminate glasses doped with different concentrations of neodymium dioxide and melted under v acuum conditions to remove water has been measured by using mode-misma tched thermal lens spectrometry. It has been shown that the thermal le ns signal amplitude is linearly dependent on neodymium concentrations up to 4.0 wt %, changing significantly from 4.5 to 5.0 wt %, indicatin g that there was quenching of the fluorescence only above 4.0 wt % neo dymium dioxide. The quantitative treatment for the thermal lens effect provided the absolute value of the sample's fluorescence quantum effi ciency. The technique is simple to perform and can be applied for a wi de range of fluorescent materials. [S0163-1829(98)00714-0].