Laser selective spectroscopy of europium complex embedded in colloidal silica spheres

Efficient and Robust Europium(III)-Based Hybrid Lanthanide Scintillators for Advanced X-Ray Imaging

Scintillators that convert ionizing radiation into low-energy photons are essential for medical diagnostics and industrial inspections. Despite advances in X-ray scintillators, challenges remain in achieving high efficiency, environmental compatibility, stability, and flexibility. Here, we present experimental investigations of a new type of europium(III)-based hybrid ternary complex scintillators for improved X-ray detection and imaging. Benefiting from the synergistic interaction between dual organic ligands and lanthanide ions, the Eu(TTA)3Phen complex demonstrates exceptional radioluminescence and light yield under X-ray excitation, with a detection limit of 19.97 nGy s-1, well below typical radiation doses used in medical diagnostics. Moreover, lanthanide complex Eu(TTA)3Phen exhibited excellent thermal and photostability, showing minimal degradation even after extended X-ray exposure. By integrating with flexible polymer matrices, a high-transmission Eu(TTA)3Phen-PMMA composite film was fabricated for X-ray radiography, demonstrating high spatial resolution (<10 um) and superior image quality across various target samples. These findings hold substantial promise for next-generation X-ray imaging applications, offering high sensitivity, stability, flexibility, and versatility, making them ideally suited for advanced radiographic systems.

Elemental and particle size fractionation during the transport of Eu(III)-silicate colloids in water-saturated porous media

Actinides (An)-bearing colloids could facilitate An migration in the environment. However, little is known about the transport behavior of An(III)-silicate colloids, which are readily formed by the reaction of An3+ with silicic acid under environmental conditions. Column experiments were conducted to investigate the transport of Eu(III)-silicate colloids (chemical analog of An(III)-silicate colloids) in water-saturated porous media as a function of pH, ionic strength (IS) and the presence of fulvic acid (FA). The results showed that colloid transport was more favorable at relatively low IS (≤ 50 mM) and high pH levels (pH ≥ 7). The presence of FA (5-10 mg/L) significantly enhanced the colloid transport. Under high IS (≥ 100 mM), the transport feature of colloids was turned from blocking to ripening due to the on-going aggregation of colloids. Additionally, an interesting elemental fractionation, i.e., a discrepancy in the breakthrough curves (BTCs) with respect to the C/C0 values of Si and Eu, was observed in the IS of 100-500 mM. A detailed investigation indicated that the elemental fractionation could be attributed to the partial Si dissolution of the colloids, the heterogeneity of the colloid size and element composition, and particle size fractionation during colloid transport. Extended Derjaguin-Landau-Verwey-Overbeek interaction energy calculations and convective-dispersive equation modeling were performed to illustrate variations in the colloid transport profiles. These findings illustrate the importance of Si dissolution in the migration of metal-silicate colloids and highlight the significant influence of the heterogeneity of colloid size and composition on the transport/migration behavior of colloids in the environment.

Design of Multi-Luminescent Silica-Based Nanoparticles for the Detection of Liquid Organic Compounds

Tracer testing in reservoir formations is utilised to determine residual oil saturation as part of optimum hydrocarbon production. Here, we present a novel detection method of liquid organic compounds by monodisperse SiO2 nanoparticles (NPs) containing two luminophores, a EuIII:EDTA complex and a newly synthesised fluorophore based on the organic boron-dipyrromethene (BODIPY)-moiety. The particles exhibited stable EuIII PL emission intensity with a long lifetime in aqueous dispersion. The fluorescence of the BODIPY was also preserved in the aqueous environment. The ratiometric PL detection technique was demonstrated by using toluene and 1-octanol as model compounds of crude oil. The optimal synthesis conditions were found to give NPs with a diameter of ~100 nm, which is suitable for transport through porous oil reservoir structures. The cytotoxicity of the NPs was confirmed to be very low for human lung cell and fish cell lines. These findings demonstrate the potential of the NPs to replace the hazardous chemicals used to estimate the residual oil saturation. Moreover, the ratiometric PL detection technique is anticipated to be of benefit in other fields, such as biotechnology, medical diagnostics, and environmental monitoring, where a reliable and safe detection of a liquid organic phase is needed.

Dye-sensitized lanthanide containing nanoparticles for luminescence based applications

Due to their exceptional luminescent properties, lanthanide (Ln) complexes represent a unique palette of probes in the spectroscopic toolkit. Their extremely weak brightness due to forbidden Ln electronic transitions can be overcome by indirect dye-sensitization from the antenna effect brought by organic ligands. Despite the improvement brought by the antenna effect, (bio)analytical applications with discrete Ln complexes as luminescent markers still suffers from low sensitivity as they are limited by the complex brightness. Thus, there is a need to develop nano-objects that cumulate the spectroscopic properties of multiple Ln ions. This review firstly gives a brief introduction of the spectral properties of lanthanides both in complexes and in nanoparticles (NPs). Then, the research progress of the design of Ln-doped inorganic NPs with capping antennas, Ln-complex encapsulated NPs and Ln-complex surface functionalized NPs is presented along with a summary of the various photosensitizing ligands and of the spectroscopic properties (excited-state lifetime, brightness, quantum yield). The review also emphasizes the problems and limitations encountered over the years and the solutions provided to address them. Finally, a comparison of the advantages and drawbacks of the three types of NP is provided as well as a conclusion about the remaining challenges both in the design of brighter NPs and in the luminescence based applications.