Biomedical Engineering Reference
In-Depth Information
Figure 15.7
(a) Sketch of experimental setup, showing the modified
confocal configuration to measure photoluminescence from the sample at
different locations with respect to the excitation spot. Two scanning stages,
SS1 and SS2, were used to perform sample or the laser point scanning
acquisitions. A
λ
/2 plate was used to control the polarization axis of the
laser light along or normal to the nanowire, and a confocal pin hole (CPH)
was inserted to get spatial resolution better than 0.6
μ
m (b) Bright field
optical image of the nanowire region (the size of the unsaturated laser spot
is smaller than 0.7
μ
m). (c) SEM images of the nanowire with nanorods
at one end (d) Conventional confocal photoluminescence map of the same
regionasdisplayedin(c)demonstratingthatnanorodsaresolelylocatedat
the left end of the nanowire.
modified confocal microscope with two scanning stages with nm
precision. One (SS1) was used in confocal imaging mode to map
the region around the nanowires in 250 nm steps in both
x
-and
y
-directions of the sample surface plane, the other (SS2) allowed
to scan or set the position of the laser spot in off-axis positions
withinthefieldofviewofthe100
×
objectivelens.Inparticular,this
configurationenabledlaserexcitation(
λ
=
488nm)attheleftendof
thenanowirewherethenanorodsweredeposited,andtherecording
of the emissionspectra at the opposite nanowire end.
15.3.3
Theoretical Modeling of Plasmon Propagation in Au
Nanowire
The computational simulations were performed by using the
FEM method (Comsol Multiphysics) with perfectly matched layer
