Relaxation Processes in Rare-Earth-Doped a-NaYF₄ Nanoparticles by Nuclear Magnetic Resonance Spectroscopy

Autor(es)

Flores, Ali F. Garcia ; Munevar, Julian ; de Oliveira, Marcos ; Rettori, Carlos ; Urbano, Ricardo R. ; de Queiroz, Thiago B.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry C; v. 127, n. 37, p. 11-pg., 2023-09-11.

Resumo

NaYF4 nanoparticles (NPs) are among the most promising hosts for lanthanides in different applications as IR-to-UV upconversion and photodynamic therapy due to their crystal electric field properties and their low phonon energy. The efficiency in such applications depends on the dispersion of the ions and their local structure in the host. Paramagnetic nuclear magnetic resonance (NMR) has been one of the main tools to perform such studies, based on the comprehensiveness of the hyperfine interaction of the rare-earth (RE)' s unpaired electrons with the observed nuclei and its effects in NMR quantities, like paramagnetic shift, line broadening, and relaxation enhancement. However, it can be challenging to resolve these effects for spin systems with large dipolar or quadrupolar interactions and site heterogeneity. We hereby address these issues for RE3+-doped alpha-NaYF4 NPs of small sizes and low polydispersity [phi approximate to 7(1) nm] with Na-23 and F-19 NMR employing high-resolution techniques associated with relaxation measurements. In particular, remarkable fast relaxation rates are found for the Gd3+-doped NPs which are rationalized in terms of Solomon ' s relaxation mechanism enhanced by the long electronic relaxation time of the ion. (AU)

• Processo FAPESP: 22/02974-1 - Aspectos fundamentais do estado amorfo de compostos metalorgânicos: uma abordagem por ressonância magnética em estado sólido
• Beneficiário: Marcos de Oliveira Junior
• Modalidade de apoio: Auxílio à Pesquisa - Projeto Inicial
• Processo FAPESP: 19/09673-4 - Apoio técnico e computacional para síntese, caracterização e estudo de nanopartículas metálicas e isolantes
• Beneficiário: Alí Francisco García Flores
• Modalidade de apoio: Bolsas no Brasil - Programa Capacitação - Treinamento Técnico
• Processo FAPESP: 20/13466-1 - Design, síntese e caracterização de sistemas moleculares para colheita de luz e separação de cargas
• Beneficiário: Thiago Branquinho de Queiroz
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 17/10581-1 - Fenômenos emergentes em sistemas de dimensões reduzidas
• Beneficiário: Pascoal Jose Giglio Pagliuso
• Modalidade de apoio: Auxílio à Pesquisa - Projetos Especiais