Multi-stimulated far-UVC luminescence for solar-blind imaging

Area of Science:

• Materials Science
• Luminescence
• Solid-State Physics

Background:

• Lanthanide-doped luminescent materials are crucial for applications like stress sensing and anti-counterfeiting.
• Current materials are limited to the 380-1540 nm range, hindering applications in solar-blind imaging and concealed communication.
• There is a need for materials emitting in the far-ultraviolet C (far-UVC) region (200-230 nm).

Purpose of the Study:

• To propose guidelines for far-UVC optical design.
• To achieve multi-stimulated far-UVC luminescence in lanthanide-doped strontium fluoride (SrF2) crystals.
• To explore the potential of these materials for advanced applications.

Main Methods:

• Developed guidelines for far-UVC optical design.
• Synthesized Praseodymium (Pr3+)-doped SrF2 crystals.
• Investigated luminescence properties, including multi-stimulated emission and mechanoluminescence.

Main Results:

• Achieved multi-stimulated far-UVC luminescence at ~222 nm in Pr3+-doped SrF2, attributed to the 4f5d → 4f^2 transition.
• Demonstrated broad spectral coverage from 200 to 1700 nm by doping SrF2 with various lanthanides (Ce3+, Nd3+, Sm3+, Eu2+,3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+).
• Observed self-recoverable mechanoluminescence and stimulated emission after X-ray irradiation.

Conclusions:

• Pr3+-doped SrF2 crystals are effective for generating far-UVC luminescence.
• SrF2 exhibits high tolerance for various lanthanide dopants, enabling broad spectral emission.
• These materials offer unique opportunities for high-contrast marking and structural health monitoring in demanding environments.