Temperature is a central concept in thermodynamics and one the most important parameters for describing phenomena in macro-, micro- and even in nanometer scale. Obtaining temperature at the nanoscale has become a widespread area, since its a crucial parameter for several emergent applications, such as intracellular temperature fluctuations and microfluidics. Light based thermometers are non-invasive methods to determine temperature and are based on a change of one spectroscopic feature with the thermal energy variation, like the position of a peak, the intensity of one or more transitions or even the variation of the excited state lifetime of a certain emission. LiYF4 has been described as a highly efficient host for upconversion emission, especially compared with other fluoride or oxide hosts, exhibiting a strong emission in the visible region when excited in the near infrared providing the adequate doping ions. Here, we describe luminescent based thermometry of LiYF4 nanoparticles on two different media; oleic acid capped were used as a primary thermometer in cyclohexane whereas cysteine modified nanocrystals were used in an aqueous dispersion, both of them using the upconversion intensity ratio of the 2H11/2 4I15/2 and 4S3/2 4I15/2 emissions of Er3+ ions using 980 nm excitation.
João Marcos Gonçalves
Chemistry degree in 2012 at University of São Paulo in Ribeirão Preto.
Masters degree in Chemistry at Instituto de Química, UNESP in Araraquara under supervision of Prof. Dr. Sidney José Lima Ribeiro. Developed an electrochemical immunosensor for an Alzheimer’s disease related peptide.
PhD in progress at University of São Paulo in Ribeirão Preto with supervision of Prof. José Maurício Almeida Caiut with the objective of studying lanthanide doped lithium yttrium fluoride nanoparticles for nanothermometry and heat generation in gold modified upconversion nanoparticles.