Efficient immobilization of silver nanoparticles on metal substrates through various thiol molecules to utilize a gap mode in surface enhanced Raman scattering |
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Affiliation: | 1. Laboratório de Nanoestruturas Plasmônicas, Núcleo de Espectroscopia e Estrutura Molecular, Departamento de Química, Universidade Federal de Juiz de Fora, R. José Lourenço Kelmer s/n, Martelos, CEP 36036-900, Juiz de Fora, MG, Brazil;2. Departamento de Física, Universidade Federal de Juiz de Fora, R. José Lourenço Kelmer s/n, Martelos, CEP 36036-900, Juiz de Fora, MG, Brazil;1. Amogreentech Co. Ltd., Gangneung Science Industry Park, Gangneung 210-340, Republic of Korea;2. Department of Chemistry, Gangneung-Wonju National University, Gangneung 210-702, Republic of Korea;1. Department of Physics, Indian Institute of Technology, Kharagpur 721302, India;2. Department of Physics, Indian Institute of Technology, Patna 800013, India;1. Department of Physics, Malaviya National Institute of Technology Jaipur, JLN Marg, Jaipur, 302017, Rajasthan, India;2. Department of Physics, The LNM Institute of InformationTechnology, Jamdoli, Jaipur, 302031, India |
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Abstract: | To utilize a gap mode in surface enhanced Raman scattering, we elucidated the interaction between adsorbed species and Ag nanoparticles (AgNPs). Various thiol molecules such as normal alkanethiols, thiols with a phenyl, cyclohexane or naphthalene ring on Ag films immobilized AgNPs through van der Waals force, and electrostatic interaction. Immobilized AgNPs provided enormous Raman enhancement by a factor of 107–1010 for thiol molecules at a nanogap, in consistent with that anticipated by finite difference time domain calculations. Only alkanethiols with a tert-methyl group and those with a carboxylic group did not immobilize any AgNPs probably owing to steric hindrance. A gap mode is relevant for a variety of metals even with large damping like Pt and Fe, indicating a crucial role of electric multipoles in AgNPs generated by a localized surface plasmon and induced mirror images in metal substrates for markedly enhanced electric field at a nanogap. |
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Keywords: | Surface enhanced Raman scattering Gap mode Silver nanoparticles Metal substrates Thiols |
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