Benchmarking Common Approximations for Determining
the Particle-Size Dependence of Adsorbate-Induced Localized Surface
Plasmon Resonance Shifts
- Publication date
- Publisher
Abstract
Anomalies are investigated that exist
between many long-standing
theoretical models of the optical behavior of sensors based on changes
in the localized surface plasmon resonance upon analyte adsorption.
In particular, we focus on single metal nanoparticles which represent
the core building-block of many recent sensing devices. Theoretical
approaches include the Retarded Mie theory, the Non-Retarded quasi-static-dipole
approximation, and two radiative corrections to the Non-Retarded case
(radiative damping and radiative damping + depolarization). We find
that the most accurate Non-Retarded approximation to the Retarded
Mie theory varies strongly on a case by case basis; anyway, for particle
radii beyond a few tens of nanometers, none of the considered approximations
represents properly the adsorbate induced plasmon shift. We also find
that the size-dependent peak shift has a complex dependence on the
metal dielectric function. Accordingly, the trend of the adsorbate-induced
plasmon peak shift as a function of the particle radius reveals an
unexpected nonmonotonic behavior. We eventually identify an interesting
range of particle radii over which the adsorbate-induced plasmon shift
is unaffected by the particle size. Moreover, we give examples where
nanoparticle batches with large size dispersion provide higher sensor
reproducibility than monodisperse samples. On the other hand, in light
of our findings, single particle measurements are pivotal to disclose
the exact structure of the peak shift trend as a function of the particle
radius