APPLICATION OF LASER-DIODES AND ULTRABRIGHT LIGHT-EMITTING-DIODES FORTHE DETERMINATION OF FLUORESCENCE LIFETIMES IN THE NANO-SECOND AND SUBNANOSECOND REGION

Fluorescence lifetime measurements are often required for investigatio ns of photoinduced electron transfer reactions. In general complicated and expensive experimental set-ups are necessary for these measuremen ts. Using semiconductor light sources, such as laser diodes and ultrab right light emitting diodes, we have developed a new experimental meth od for the determination of fluorescence lifetimes in the nano- and su bnanosecond region. Measurements using a laser diode as excitation lig ht source have been performed with oxazine dyes in several different s olvents in the range of 0.4 to 4 ns. Investigations of Ru(II)-complexe s in various solvents applying ultrabright blue light emitting diodes showed lifetimes in a range of 400 to 900 ns. As the evaluation of the data is exclusively based on the time shift but not on light intensit y, the method is free from interference, like long term drafts in ligh t source or detector. Therefore it can be used for industrial and medi cal sensor applications.