Ultrafast Laser Filament-induced Fluorescence Spectroscopy of Uranyl Fluoride

Area of Science:

• Laser-induced spectroscopy
• Nuclear chemistry
• Remote sensing technologies

Background:

• Uranyl fluoride (UO2F2) is a key indicator of uranium enrichment facility operations.
• Current detection methods for UO2F2 are limited in range and application.
• Laser-induced fluorescence (LIF) has shown potential for UO2F2 detection.

Purpose of the Study:

• To investigate the use of ultrafast laser filamentation combined with LIF for remote UO2F2 detection.
• To characterize the luminescence properties of UO2F2 under ultrafast laser excitation.
• To assess the feasibility of this technique for treaty verification and remediation efforts.

Main Methods:

• Excitation of UO2F2 luminescence using a Ti:sapphire laser's second harmonic.
• Utilizing conical emission from ultrafast laser filamentation in air for UO2F2 excitation.
• Measuring luminescence decay rates under varying laser intensities (1.0-1.6 × 10^11 W cm^-2).

Main Results:

• Demonstrated remote detection of UO2F2 using ultrafast laser filamentation and LIF.
• Observed luminescence decay rates in the range of 4.3-5.6 × 10^4 s^-1.
• Identified a saturated prompt decay component due to dense excited states under ultrafast excitation.

Conclusions:

• Ultrafast laser filamentation coupled with LIF significantly enhances remote UO2F2 detection capabilities.
• The technique shows promise for real-time monitoring and verification applications.
• Reproducible decay rate measurements support the application in remote sensing for UO2F2.