title: Highly-sensitive Eu(3+) ratiometric thermometers based on excited state absorption with predictable calibration.
abstract: Temperature measurements ranging from a few degrees to a few hundreds of Kelvin are of great interest in the fields of nanomedicine and nanotechnology. Here, we report a new ratiometric luminescent thermometer using thermally excited state absorption of the Eu(3+) ion. The thermometer is based on the simple Eu(3+) energy level structure and can operate between 180 and 323 K with a relative sensitivity ranging from 0.7 to 1.7% K(-1). The thermometric parameter is defined as the ratio between the emission intensities of the (5)D0 → (7)F4 transition when the (5)D0 emitting level is excited through the (7)F2 (physiological range) or (7)F1 (down to 180 K) level. Nano and microcrystals of Y2O3:Eu(3+) were chosen as a proof of concept of the operational principles in which both excitation and detection are within the first biological transparent window. A novel and of paramount importance aspect is that the calibration factor can be calculated from the Eu(3+) emission spectrum avoiding the need for new calibration procedures whenever the thermometer operates in different media.
authors.affiliation: Departamento de Química Fundamental-CCEN-UFPE, Cidade Universitária, Recife-PE, 50670-901, Brazil. adelmosaturnino@hotmail.com.
authors.forename: Adelmo S
authors.initials: AS
authors.lastname: Souza
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo - USP, CEP 13560-970, São Carlos, SP, Brazil.
authors.forename: Luiz A O
authors.initials: LA
authors.lastname: Nunes
authors.affiliation: Instituto de Química, Universidade de São Paulo, 05508-900 São Paulo, SP, Brazil.
authors.forename: Ivan G N
authors.initials: IG
authors.lastname: Silva
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo - USP, CEP 13560-970, São Carlos, SP, Brazil.
authors.forename: Fernando A M
authors.initials: FA
authors.lastname: Oliveira
authors.affiliation: Departamento de Química Fundamental-CCEN-UFPE, Cidade Universitária, Recife-PE, 50670-901, Brazil. adelmosaturnino@hotmail.com.
authors.forename: Leonis L
authors.initials: LL
authors.lastname: da Luz
authors.affiliation: Instituto de Química, Universidade de São Paulo, 05508-900 São Paulo, SP, Brazil.
authors.forename: Hermi F
authors.initials: HF
authors.lastname: Brito
authors.affiliation: Centro de Química do Meio Ambiente, Instituto de Pesquisas Energéticas e Nucleares, Av. Prof. Lineu Prestes, 2242, 05508-000 São Paulo, SP, Brazil.
authors.forename: Maria C F C
authors.initials: MC
authors.lastname: Felinto
authors.affiliation: Department of Physics and CICECO Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal. lcarlos@ua.pt.
authors.forename: Rute A S
authors.initials: RA
authors.lastname: Ferreira
authors.affiliation: Departamento de Química Fundamental-CCEN-UFPE, Cidade Universitária, Recife-PE, 50670-901, Brazil. adelmosaturnino@hotmail.com.
authors.forename: Severino A
authors.initials: SA
authors.lastname: Júnior
authors.affiliation: Department of Physics and CICECO Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal. lcarlos@ua.pt.
authors.forename: Luís D
authors.initials: LD
authors.lastname: Carlos
authors.affiliation: Departamento de Química Fundamental-CCEN-UFPE, Cidade Universitária, Recife-PE, 50670-901, Brazil. adelmosaturnino@hotmail.com.
authors.forename: Oscar L
authors.initials: OL
authors.lastname: Malta