Principles of Fluorescence Spectroscopy

PRINCIPLES OF FLUORESCENCE SPECTROSCOPY 231
Figure 6.51. Frequency-domain intensity decay of Yt-base in benzene
with 6% methanol. From [103].
equivalent fits. In such cases one must rely on other information
to select the more appropriate model. In this case the
lifetime distribution model seems preferable because there
is no reason to expect two unique decay times in a solvent
mixture.
6.12. SUMMARY OF SOLVENT EFFECTS
Table 6.4. Multi-Exponential Analysis of the Intensity Decays of
Yt-Base in Benzene/Methanol Mixtures a
A quantitative description of the effects of environment on
fluorescence emission spectra is perhaps the most challenging
topic in fluorescence spectroscopy. No single theory or
type of interactions can be used in all circumstances. A
number of factors affect the emission including:
Number of
% Methanol decay times τ i (ns) α i f i x 2 R
0 9.67 1.0 1.0 1.3
4 1 8.80 1.0 1.0 3.2
2 3.67 0.061 0.026 1.2
9.10 0.939 0.974
6 1 8.36 1.0 1.0 8.9
2 3.50 0.113 0.048 1.2
8.92 0.887 0.952
10 1 7.23 1.0 1.0 4.9
2 2.99 0.082 0.034 1.0
7.56 0.918 0.966
100 1 6.25 1.0 1.0 1.9
a From [103].
Figure 6.52. Lifetime distribution analysis of the intensity decay of
Yt-base in pure methanol, pure benzene, and benzene with 6%
methanol. Revised from [103].