Elucidation of Laser-Particle Interaction through Optical Trapping of Single, Micron-Sized Particles for Nuclear Forensics and Nonproliferation

The release of radiological plumes demands the ability to perform real-time atmospheric sampling using technology capable of tracking airborne particulates to enable and guide first responders. An attractive method for standoff detection, such as Laser-Induced Breakdown Spectroscopy (LIBS), relies on optical emission techniques to identify the elemental composition by assessing species’ emission signatures. Recent efforts have utilized pulsed ns-, fs-, and fs-filament laser-produced plasmas (LPPs) to characterize generated aerosol plumes acting as surrogates for radiological releases. Given the stochastic nature of plasma-particle interactions, LIBS for aerosolized samples remains a challenge, driving work aimed at improving detection limits and collection reproducibility. However, an important aspect of enhancing the characterization of aerosol samples via LPPs is understanding both plasma-particle energy transference and excitation/dissociation mechanisms. In this work, we aim to assess complex laser-particle interactions occurring using both fs-lasers and ns-lasers with spatially isolated CuO, AlN, and actinide particles via optical trapping. In this proceeding, we discuss advancements in establishing a universal optical trap utilizing a counter-propagating Bessel beam configuration and present a procedure for generating a tunable Bessel beam as well as steps to ensure precise alignment for optical trapping. The scope of this work is to elucidate the interaction between the impinging laser and suspended particles to broaden our knowledge, from the fundamentals of laser-matter interactions to applications in atmospheric sensing of low-concentration aerosols, for application in nuclear forensics, nonproliferation, and reactor monitoring.