Multiscale Theoretical Modeling of Plasmonic Sensing of Hydrogen Uptake in Palladium Nanodisks.

We study theoretically the optical properties of palladium nanodisks during hydrogen uptake. A combination of an ab initio quantum mechanical description of the Pd-H dielectric properties and a full electrodynamical study of light scattering in the H-modified Pd nanodisks allows us to trace the shift of the localized surface plasmon as a function of the H concentration in the Pd-H disk. We follow the evolution of the plasmon peak energy for different admixtures of the Pd-H α and β phases and interpret quantitatively the experimental sensitivity of the plasmon energy shift to the structural inhomogeneity upon H absorption. Our multiscale theoretical framework provides a solid background for plasmonic sensing of structural domains, as well as for identifying H saturation conditions in metal hydride systems.