Nanoscale thermal characterization of high aspect ratio gold nanorods for photothermal applications at λ = 1.5 μm.

We synthetized gold nanorods that present a high aspect ratio (>10) and possess a surface plasmon resonance in the near-infrared, in the 1300–1600 nm spectral range. Using a single Er³⁺-doped NaYF₄ nanocrystal deposited on their surface, we measured the temperature increase of a few nanorods excited at their surface plasmon resonance wavelength. We observed a temperature increase of more than 30 °C for an excitation power density of 3 mW/μm². This experiment shows that a very small amount of nanorods can be used for obtaining an intense and localized photothermal effect. Applications can be found in the design of inexpensive infrared photodetectors and photothermal therapy in the third biological window. In addition, the association of gold nanorods with an Er³⁺ doped nanocrystal constitutes a very interesting hybrid heater/temperature sensor. [ABSTRACT FROM AUTHOR]