Modeling blue to UV upconversion in β-NaYF₄:Tm³.

Area of Science:

• Materials Science
• Solid-State Physics
• Luminescence

Background:

• Upconversion luminescence in rare-earth doped materials is crucial for various photonic applications.
• Existing literature presents conflicting mechanisms for upconversion in Tm³⁺-doped β-NaYF₄.

Purpose of the Study:

• To investigate and clarify the upconversion mechanisms in Tm³⁺-doped β-NaYF₄.
• To compare the validity of different theoretical models in describing experimental data.

Main Methods:

• Experimental synthesis of Tm³⁺-doped β-NaYF₄ samples.
• Spectroscopic analysis including UV-Vis emission and two-color excitation.
• Analysis of luminescence decay curves using Inokuti-Hirayama, average rate equation, and microscopic rate equation models.

Main Results:

• Observed UV upconversion luminescence at 361 nm upon blue excitation at 473 nm.
• Demonstrated that energy migration is negligible in these samples.
• Showed that the microscopic rate equation model accurately fits experimental decay curves.

Conclusions:

• The microscopic rate equation model provides an accurate description of the upconversion process.
• This model reveals the strength and multipolarity of interactions, identifying the most probable upconversion mechanism.
• Negligible energy migration necessitates advanced models for accurate analysis.