the temporal change in the fluorescence spectrum was monitored. Figure 14.10b
shows the 1st, 9th, 25th, and 36th fluorescence spectrum obtained during the CPL
measurements. It can be seen that even after 36 accumulations, no change in the
spectral shape occurred.
Figure 14.11 shows CD and CPL spectra of this GFP. The CD and absorption
spectra were obtained with 30 μg/mL of the sample concentration and 20-mm path
length. The CD originated from aromatic amino acid side chains and was observed in
the near-ultraviolet region, whereas the optical absorption and CPL originating from
functional groups emitting green fluorescence appear in the visible region. Since g abs
and g lum are similar to each other, structural differences between the ground and
excited states of the fluorescent functional groups are considered to be very small.
Figure 14.12 shows CD and CPL spectra of enhanced GFP, which offers higherintensity emission with respect to wild-type GFP. In this case also, g abs and g lum are
small and similar to each other, indicating that structural differences between the
ground and excitation states are very small.
14.5.4 CPL Measurements of Solid Sample
Finally, we introduce a method for measuring CPL for a solid sample. When
circularly polarized light-emitting materials are used for displays and illumination,
these materials are expected to be not liquids but solids. Therefore, it is necessary to
0
0.8
0.2
0.4
0.6
470
570
500
520
540
Wavelength [nm]
470
570
500
520
540
CPL [mdeg]
Wavelength [nm]
1 mdeg
Accumulations
4 times
9 times
25 times
36 times
FL [Arb. Unit]
(a)
(b)
Excitation bandwidth=12 nm
Accumulations
4 times
9 times
25 times
36 times
Fig. 14.10 CPL and fluorescence spectra of wild-type GFP. (a) Accumulation dependence on CPL
spectra of GFP. (b) Sample stability check during CPL spectra accumulation
14 Principles and Applications of Circularly Polarized Luminescence. . .
319
shows the 1st, 9th, 25th, and 36th fluorescence spectrum obtained during the CPL
measurements. It can be seen that even after 36 accumulations, no change in the
spectral shape occurred.
Figure 14.11 shows CD and CPL spectra of this GFP. The CD and absorption
spectra were obtained with 30 μg/mL of the sample concentration and 20-mm path
length. The CD originated from aromatic amino acid side chains and was observed in
the near-ultraviolet region, whereas the optical absorption and CPL originating from
functional groups emitting green fluorescence appear in the visible region. Since g abs
and g lum are similar to each other, structural differences between the ground and
excited states of the fluorescent functional groups are considered to be very small.
Figure 14.12 shows CD and CPL spectra of enhanced GFP, which offers higherintensity emission with respect to wild-type GFP. In this case also, g abs and g lum are
small and similar to each other, indicating that structural differences between the
ground and excitation states are very small.
14.5.4 CPL Measurements of Solid Sample
Finally, we introduce a method for measuring CPL for a solid sample. When
circularly polarized light-emitting materials are used for displays and illumination,
these materials are expected to be not liquids but solids. Therefore, it is necessary to
0
0.8
0.2
0.4
0.6
470
570
500
520
540
Wavelength [nm]
470
570
500
520
540
CPL [mdeg]
Wavelength [nm]
1 mdeg
Accumulations
4 times
9 times
25 times
36 times
FL [Arb. Unit]
(a)
(b)
Excitation bandwidth=12 nm
Accumulations
4 times
9 times
25 times
36 times
Fig. 14.10 CPL and fluorescence spectra of wild-type GFP. (a) Accumulation dependence on CPL
spectra of GFP. (b) Sample stability check during CPL spectra accumulation
14 Principles and Applications of Circularly Polarized Luminescence. . .
319