Nd:YAG Near-Infrared Luminescent Nanothermometers

A. Benayas, B. del Rosal A. Pérez-Delgado, K. Santacruz-Gómez,D. Jaque, G. A. Hirata and F. Vetrone

Advanced Optical Materials Volume 3, Issue 5, pages 687–694, May 2015

Today we would like to present you excellent example of luminescent thermometer based on Nd3+ doped phosphors – YAG Nd3+ nanoparticles. First of the key thing which makes this paper worth especial attention is the fact of use transition between R1 and R2 Stark component of 4F3/2 state and Z5 component of 4I9/2 ground state. Why? In case of YAG these two lines are very well separated to each other (938 nm 945 nm, respectively) due to large crystal field splitting comparing to other Nd3+ doped host. Hence the measurement of the temperature is burdened with smaller error. Moreover the sensitivity of this kind of thermometer is relatively high (0.15% comparing to the other Nd3+ doped examples). The second important aspect of this paper is the strong emphasis put on the examples of application of Nd3+:YAG nanoparticles for temperature sensing. In a first example was drop of an aqueous dispersion of Nd:YAG nanoparticles onto micro sized copper wire in order to evaluate the Joule-induced changes of the wire’s temperature. Obtained results are of comparable quality of ones obtained using IR camera. Another example was temperature sensing of optofluidics. It was proven that high resolution thermal image of temperature gradient induced by 1480 nm excitation beam was obtained. In the last example aqueous solution of ND:YAG nanoparticles was injected into chicken breast (5mm under its surface) and the changes of the luminescence spectra after its exposure on pulsed hot air flow was monitored. It confirms that by use of this kind of particles fast and accurate sensing of the temperature on subsurface level is possible.
Due to the fact that this article describes not only physical basis of temperature measurement using this kind of particles but also shows proof-of-concept of its application this paper is highly recommended to read.