Chemistry Reference
In-Depth Information
FIGURE 12.5
(Left side) Wide-field image at 0.64
U
and schematic representation of
compound
4
without the presence of DVB cross-linker. (Right side) Wide-field image at
0.65
U
and schematic representation of compound
4
with 1% of DVB cross-linker present. For
the schematic representation, the dyes are shown as circles for which the color indicates their
current velocity (white: too fast for detection bywide-fieldmicroscopy, yellow: slowenough for
wide-field microscopy, red: very slow/immobilized). Copyright from Ref. [44]. (See the color
version of this figure in Color Plates section.)
12.5 REDOX/ELECTRON TRANSFER PROBES
Studying electron transfer with single-molecule fluorescence microscopy is chal-
lenging since in contrast to fluorescence resonance energy transfer where fluores-
cence is emitted mainly from the acceptor chromophore, a highly efficient electron
transfer usually leads to a strong quenching of the fluorescence of the emitting
chromophore. Thus, reports on single-molecule photo-induced electron transfer are
rather limited in number [45-47]. A particular situation of electron transfer refers to
the case when the locally excited state (LES) and the charge-separated state (CSS) are
close in energy. In this case, upon excitation, the LES deactivates mainly via forward
