  We use a network of molecularly linked gold nanoparticles (NPSAN:
nanoparticles self-assembled network) to demonstrate the electrical detection
(conductance variation) of a plasmon-induced isomerization (PII) of azobenzene
derivatives (azobenzene bithiophene : AzBT). We show that PII is more efficient
in a 3D-like (cluster-NPSAN) than in a purely two-dimensional NPSAN (i.e., a
monolayer of AzBT functionalized Au NPs). By comparison with usual optical
(UV-visible light) isomerization of AzBT, the PII shows a faster (a factor
about 10) isomerization kinetics. Possible PII mechanisms are discussed:
electric field-induced isomerization, two-phonon process, plasmon-induced
resonant energy transfer (PIRET), the latter being the most likely.
