BUSCADOR RECOLECTA

Measuring light irradiance, or power density, within a material is essential for ensuring the precision, efficiency, and safety of light-based technologies, such as photodynamic therapies, optical sensing, and material processing. However, this task becomes particularly challenging in scenarios involving highly scattering or absorbing media, dynamic systems with varying properties, or confined and hardly accessible compartments. These challenges can be addressed by using colloidal luminescent nanomaterials with luminescence lifetimes strongly dependent on excitation irradiance. Building on this, an upconversion lifetime-based Nano Irradiance Meter (nIM) is proposed, employing, on SrYb3 +F5:
@CaF2 upconverting nanoparticles. This nIM operates within the first biological window and allows the direct estimation of laser irradiance, without prior knowledge of the area illuminated by the excitation beam. The feasibility of the sensor is validated through a calibration process, correlating the lifetime of the 770 nm upconversion luminescence of Tm3 + ions with the 967 nm excitation irradiance. The sensor achieved a sensitivity of 0.9% W−1 cm2 at low irradiances (≈17 W cm−2) and 0.008% W−1 cm2 at high irradiances (≈5 kW cm−2), surpassing previously reported results based on ratiometric luminescence approaches. Finally, its robust performance under real-life conditions across various media is demonstrated.

This dataset contains the experimental procedures, characterization data, and validation results for the surface functionalization of silica-coated upconversion nanoparticles (UCNPs@SiO₂) used in the publication A scalable approach for tailoring silica shells: from synthesis to stability of upconversion nanoparticles.

The upconversion luminescence (UCL) lifetime has a wide range of applications, serving as a critical parameter for optimizing the performance of upconversion nanoparticles (UCNPs) in various fields. It is crucial to understand that this lifetime does not directly correlate with the decay time of the emission level; rather, it represents a compilation of all the physical phenomena taking place in the upconversion process. To delve deeper into this, we analyzed the dependence of the UCL lifetime on the excitation pulse width for β-NaYF4:Yb3+,Er3+ nanoparticles. The results revealed a significant increase in the UCL lifetime with both the excitation pulse width and the excitation intensity. The laser fluence was identified as the parameter governing the UCL decay dynamics. We showcased the universality of the pulse-width-dependent UCL lifetime phenomenon by employing UCNPs of various sizes, surface coatings, host matrices, Yb3+ and Er3+ ratios, and dispersing UCNPs in different solvents. Theoretical explanations for the experimental findings were derived through a rate equation analysis. Finally, we discussed the implications of these results in UCNP-FRET (Förster resonance energy transfer)-based applications.