Spectral Properties Of Laser Dyes At Varying Temperatures

Spectral properties of laser dyes 4-methyl-7-(4-morpholinyl)-2H-pyrano[2,3-b]-pyridin-2-one (LD-425) and 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoromrthyl)-2H-pyrano[2,3b][1,8]naphthyridin-2-one (LD-489) have been investigated in the temperature range 25 degrees C 65 degrees C by steady-state and transient methods. Fluorescence intensity decreases with increase in temperature, with fluorescence band maxima shifted towards shorter wavelengths in both dyes. Furthermore, fluorescence lifetime has decreased with increase in temperature for LD-425, whereas it remained constant with change in temperature for LD-489. The possible deactivation mechanisms are discussed. The quenching effect of these dyes in the presence of aniline at different temperatures has been studied and the Stern-Volmer (S-V) plots are nonlinear, showing positive deviation. It has been observed that the dynamic quenching constant increases with temperature, whereas the static quenching constant is independent of temperature.