Fig. 3.

Top: photostability of ICG–HSA on a roughened silver electrode and on an unused silver electrode, measured using the same excitation power at 760 nm, and (bottom) with the laser power adjusted to give the same initial fluorescence intensities. In all measurements, vertically polarized excitation was used, whereas fluorescence emission was observed at the magic angle; i.e., 54.70. It should be noted there is a background of about 40 cps that has not been subtracted in these intensity plots.