Time-resolved circularly polarized luminescence of Eu³⁺ -based systems

Area of Science:

• Coordination Chemistry
• Materials Science
• Spectroscopy

Background:

• Chiral Europium (Eu³⁺) complexes are typically analyzed using circularly polarized luminescence (CPL) spectroscopy.
• Emission lifetimes of CPL components are generally assumed to be identical in homogeneous samples.
• Previous studies have not focused on potential differences in CPL emission lifetimes.

Purpose of the Study:

• To investigate the phenomenon of differing emission lifetimes between left and right circularly polarized luminescence in chiral Eu³⁺ systems.
• To explore the potential of CPL lifetime measurements as a tool for assessing the homogeneity of chiral lanthanide complexes.
• To demonstrate this effect in specific Eu³⁺ complexes and nanocrystals.

Main Methods:

• Circularly polarized luminescence spectroscopy was employed to measure emission lifetimes.
• Analysis focused on the differences in decay rates between the two circular polarization components.
• The study examined the chiral complex Eu(facam)₃ and Eu³⁺-doped chiral TbPO₄·D₂O nanocrystals.

Main Results:

• A measurable difference in emission lifetimes between the two circular polarization components was observed for Eu(facam)₃.
• This lifetime difference is attributed to the heterogeneity of the complex structures within the sample.
• Similar lifetime discrepancies were also observed in Eu³⁺-doped chiral TbPO₄·D₂O nanocrystals.

Conclusions:

• The heterogeneity of chiral lanthanide complexes can lead to distinct emission lifetimes for different circular polarizations.
• Measuring these CPL lifetime differences provides a novel approach to evaluate the homogeneity of chiral lanthanide systems.
• This spectroscopic method offers a unique advantage where other techniques may be insufficient for homogeneity assessment.