(color online) FOM of individual nanospheres and nanocubes on a substrate. (a1) and (a2) LSPR peaks of a single Ag nanoparticle in different solvent environments, showing the linear relationship between the solvent RI and the LSPR wavelength, for which the FOM is 4.1.^[42] (b1) and (b2) Scattering spectra of a Ag nanocube-on-glass in different dielectric environments. The narrower peak 1, quadrupole mode, sustains a sensing FOM of 5.4.^[16] Reprinted with permission from Copyright 2003, 2005 American Chemical Society.