Chlorophyll b in solution: fluorescence lifetimes, absorption and emission spectra as criteria of purity

The fluorescence lifetime τF of chlorophyll b (chl b) was measured in various solvents. The excitation wavelength was varied and the fluorescence was measured at various wavelengths in the spectral range 650–710 nm. For freshly prepared pure chl b solutions, τF, does not depend on the excitation and emission wavelengths. However, for contaminated chl b solutions, a significant dependence of τF on the emission wavelength is observed. In this case there are also clear changes in the molar absorption coefficients of the main absorption bands which correlate with the formation of degradation products of chl b.