Quantifying the sensitivity of multipolar (dipolar, quadrupolar, and octapolar) surface plasmon resonances in silver nanoparticles: the effect of size, composition, and surface coating

The effect of composition, size, and surface coating on the sensitivity of localized multipolar surface plasmon resonances has been spectroscopically investigated in high-quality silver colloidal solutions with precisely controlled sizes from 10 to 220 nm and well-defined surface chemistry. Surface plasmon resonance modes have been intensively characterized, identifying the size-dependence of dipolar, quadrupolar, and octapolar modes. Modifications of the NP's surface chemistry revealed the higher sensitivity of large sizes, long molecules, thiol groups, and low-order resonance modes. We also extend this study to gold nanoparticles, aiming to compare the sensitivity of both materials, quantifying the higher sensitivity of silver.We acknowledge financial support from the Spanish Ministerio de Ciencia e Innovacion (MICINN) (MAT2012-33330) and from the Catalan Agencia de Gestio d’Ajuts Universitaris i de Recerca (AGAUR) (2014-SGR-612). Financial support from the QNano (INFRA-2010-262163) and FutureNanoNeeds (FP7-NMP-2013-LARGE-7) Projects financed by the European Community under the FP7 Capacities Programme are gratefully acknowledged. N.G.B. acknowledges financial support by MINECO through the Ramon y Cajal program (RYC2012-10991) and by the European Commission Seventh Framework Programme (FP7) through the Marie Curie Career Integration Grant (322153-MINE).Peer Reviewe