title: Unconventional Increase in Non-Radiative Transitions in Plasmon-Enhanced Luminescence: A Distance-Dependent Coupling.
abstract: We used Optically Stimulated Luminescence (OSL) from X-ray-irradiated sodium chloride nanocrystals to investigate how silver nanoparticle (AgNP) films enhanced luminescence. We controlled the emitter-AgNP distance and used the OSL intensity and decay times to explore the plasmonic interactions underlying the enhanced luminescence. Both intensity and decay times depended on the emitter-AgNP distance, which suggested that a mechanism involving energy transfer from the localized surface plasmons (LSPs) to the trapped electrons took place through a distance-dependent coupling. Compared to other plasmon-enhanced mechanisms, the energy transfer observed here occurred in the opposite bias: LSP relaxation stimulated electron transfer from non-optically active traps to optically active traps, which culminated in enhanced emission. Therefore, a different mechanism of plasmonic coupling converted optically unreachable electrons into useful luminescence information.
authors.affiliation: Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brasil.
authors.forename: Eder José
authors.initials: EJ
authors.lastname: Guidelli
authors.affiliation: Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brasil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Ramos
authors.affiliation: Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brasil.
authors.forename: Oswaldo
authors.initials: O
authors.lastname: Baffa