
343Optical Nanosensors
must be chosen carefully to ensure that the incident laser light excites the
LSPR. The term “enhancement factor” is used to describe the magnitude to
which the SERS effect increases the intensity of the Raman scattering for a
given experimental system. The enhancement factor is calculated by divid-
ing the SERS spectral intensity by the normal Raman scattering intensity
after normalizing both with respect to collection time, laser power, and
number of molecules present in the sampling volume.
Figure 6.3 shows the principle of the technology approach for the NS based
on SERS. Molecules (unlled circles) are att