Publications by authors named "Sadaf Ehtesabi"

Article Synopsis
  • - This study explores how plasmon-driven reactions on silver nanoparticles are influenced by various factors, focusing on the protonation of 4-mercaptopyridine (4-MPY) in relation to binding modes and molecule interactions on the nanoparticle surface.
  • - Two proton sources, molecular hydrogen and water, were evaluated, revealing that the binding mode significantly impacts the thermodynamics, kinetics, and light-driven charge-transfer directionality at the 4-MPY-Ag interface.
  • - The research emphasizes the importance of electromagnetic field enhancement around the molecule, which doesn't alter the ground state thermodynamics but boosts light-driven charge-transfer and reactivity in plasmonic systems.
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Noble metal nanostructures can efficiently harvest electromagnetic radiation, which, in turn, is used to generate localized surface plasmon resonances. Surface plasmons decay, producing hot carriers, that is, short-lived species that can trigger chemical reactions on metallic surfaces. However, noble metal nanostructures catalyze only a very small number of chemical reactions.

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Noble metal nanostructures absorb light producing coherent oscillations of the metal's electrons, so-called localized surface plasmon resonances (LSPRs). LSPRs can decay generating hot carriers, highly energetic species that trigger chemical transformations in the molecules located on the metal surfaces. The number of chemical reactions can be expanded by coupling noble and catalytically active metals.

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The conversion of the thiols 4-aminothiophenol (ATP) and 4-nitrothiophenol (NTP) can be considered as one of the standard reactions of plasmon-induced catalysis and thus has already been the subject of numerous studies. Currently, two reaction pathways are discussed: one describes a dimerization of the starting material yielding 4,4'-dimercaptoazobenzene (DMAB), while in the second pathway, it is proposed that NTP is reduced to ATP in HCl solution. In this combined experimental and theoretical study, we disentangled the involved plasmon-mediated reaction mechanisms by carefully controlling the reaction conditions in acidic solutions and vapor.

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Well-designed plasmonic nanostructures can mediate far and near optical fields and thereby enhance light-matter interactions. To obtain the best overall enhancement, structural parameters need to be carefully tuned to obtain the largest enhancement at the input and output frequencies. This is, however, challenging for nonlinear light-matter interactions involving multiple frequencies because obtaining the full picture of structure-dependent enhancement at individual frequencies is not easy.

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