Chemistry Reference
In-Depth Information
FIGURE 12.23
Single-molecule fluorescence intensity trajectories on 360 nm excitation of
twomolecules of compound
13
in Zeonex. Detected photons in the TDI channel are colored red,
and those from the PMI channel are green. (a) Trajectories of the fluorescence intensity (upper
panel, red and green lines) and fluorescence decay time (lower panel, red circles) from a single
molecule of compound
13
. (b) Normalized probability densities of the survival time of single
triad molecules on 360 nm pulsed excitation (upper panel) and 490 nm pulsed excitation (lower
panel). Also shown are exponential fits (line
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symbol) to the respective histograms. (c)
Trajectories of the fluorescence intensity (upper panel, red and green lines), fractional intensity
(upper panel, gray line), and fluorescence decay time (lower panel, red and green circles) from
another single molecule of compound
13
. (d) Contour plot showing the correlation between the
single-molecule fluorescence decay times detected in the TDI and PMI channels in the region
from45 to 58 s shown in panel c, upper part. Copyright fromRef. [123]. (See the color version of
this figure in Color Plates section.)
observed in the single-molecule experiments at 490 nm laser excitation [123]. On
360 nm excitation, 20% of the interrogated single triad molecules showed such an
intermediate species. The fluorescence emitted from the TDI side is the result of
excitation energy transfer from the NMI chromophores, either by direct transfer or via
stepwise transfer through a PMI. NMI chromophores have a high probability for
triplet formation and therefore a high chance to rapidly photobleach. The higher ISC
