Effect of variation of temperature on second-derivative fluorescence spectra. Part I. Spectral changes and uncorrected temperature coefficients

The effects of variation of temperature in the range 5–45 °C on the zero-order and second-derivative excitation and emission fluorescence spectra of ten compounds have been investigated. Both the zero-order fluorescence intensities and their second-derivative amplitudes decrease linearly with increasing temperature. When the spectral measurements are not subject to interference from Raman or Rayleigh-Tyndall scattered light, the temperature coefficients of the second-derivative amplitudes are similar to or only slightly greater than those of the zero-order fluorescence intensities. Raman scatter bands of water and their second-derivative amplitudes show a small inverse temperature dependence and Rayleigh-Tyndall scatter bands and their second-derivative amplitudes show a positive temperature dependence. Raman and Rayleigh-Tyndall scatter interferences in spectral measurements result in erroneously low temperature coefficients.