TY - JOUR A1 - Stefancu, Andrei A1 - Nan, Lin A1 - Zhu, Li A1 - Chis, Vasile A1 - Bald, Ilko A1 - Liu, Min A1 - Leopold, Nicolae A1 - Maier, Stefan A. A1 - Cortes, Emiliano T1 - Controlling plasmonic chemistry pathways through specific ion effects JF - Advanced optical materials N2 - Plasmon-driven dehalogenation of brominated purines has been recently explored as a model system to understand fundamental aspects of plasmon-assisted chemical reactions. Here, it is shown that divalent Ca2+ ions strongly bridge the adsorption of bromoadenine (Br-Ade) to Ag surfaces. Such ion-mediated binding increases the molecule's adsorption energy leading to an overlap of the metal energy states and the molecular states, enabling the chemical interface damping (CID) of the plasmon modes of the Ag nanostructures (i.e., direct electron transfer from the metal to Br-Ade). Consequently, the conversion of Br-Ade to adenine almost doubles following the addition of Ca2+. These experimental results, supported by theoretical calculations of the local density of states of the Ag/Br-Ade complex, indicate a change of the charge transfer pathway driving the dehalogenation reaction, from Landau damping (in the lack of Ca2+ ions) to CID (after the addition of Ca2+). The results show that the surface dynamics of chemical species (including water molecules) play an essential role in charge transfer at plasmonic interfaces and cannot be ignored. It is envisioned that these results will help in designing more efficient nanoreactors, harnessing the full potential of plasmon-assisted chemistry. KW - chemical interface damping KW - Hofmeister effect KW - hydration layer KW - plasmonic chemistry KW - specific ion effects KW - surface-enhanced Raman scattering Y1 - 2022 U6 - https://doi.org/10.1002/adom.202200397 SN - 2195-1071 VL - 10 IS - 14 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kogikoski Junior, Sergio A1 - Tapio, Kosti A1 - Edler von Zander, Robert A1 - Saalfrank, Peter A1 - Bald, Ilko T1 - Raman enhancement of nanoparticle dimers self-assembled using DNA origami nanotriangles JF - Molecules : a journal of synthetic chemistry and natural product chemistry / Molecular Diversity Preservation International N2 - Surface-enhanced Raman scattering is a powerful approach to detect molecules at very low concentrations, even up to the single-molecule level. One important aspect of the materials used in such a technique is how much the signal is intensified, quantified by the enhancement factor (EF). Herein we obtained the EFs for gold nanoparticle dimers of 60 and 80 nm diameter, respectively, self-assembled using DNA origami nanotriangles. Cy5 and TAMRA were used as surface-enhanced Raman scattering (SERS) probes, which enable the observation of individual nanoparticles and dimers. EF distributions are determined at four distinct wavelengths based on the measurements of around 1000 individual dimer structures. The obtained results show that the EFs for the dimeric assemblies follow a log-normal distribution and are in the range of 10(6) at 633 nm and that the contribution of the molecular resonance effect to the EF is around 2, also showing that the plasmonic resonance is the main source of the observed signal. To support our studies, FDTD simulations of the nanoparticle's electromagnetic field enhancement has been carried out, as well as calculations of the resonance Raman spectra of the dyes using DFT. We observe a very close agreement between the experimental EF distribution and the simulated values. KW - surface-enhanced Raman scattering KW - DNA origami KW - resonance Raman KW - scattering KW - nanoparticle dimers Y1 - 2021 U6 - https://doi.org/10.3390/molecules26061684 SN - 1420-3049 VL - 26 IS - 6 PB - MDPI CY - Basel ER -