近日，美国加州理工学院的Lihong V. Wang及其研究团队取得一项新进展。经过不懈努力，他们实现火焰中飞秒激光-纳米粒子动力学的单脉冲超快实时同步平面成像。相关研究成果已于2024年8月29日在国际知名学术期刊《光：科学与应用》上发表。

本研究介绍了一种名为“单脉冲飞秒激光片压缩超快摄影（fsLS-CUP）”的超快成像技术，该技术专为揭示并捕捉飞秒激光与火焰中纳米粒子相互作用产生的超快动力学过程而设计，且只需单次拍摄。fsLS-CUP首次实现了每秒数十亿帧（Gfps）的实时二维（2D）成像，同时捕捉到了分别源自多环芳烃（PAHs）和碳烟粒子的激光诱导荧光（LIF）和激光诱导加热（LIH）。

此外，fsLS-CUP以惊人的250 Gfps速度提供了飞秒激光与碳烟相互作用产生的弹性光散射（ELS）的实时时空分布图。与现有的每秒仅数百万帧且需要多个激光脉冲的单次拍摄超快成像方法相比，该方法只需单个脉冲，即可以数百Gfps的速度捕捉激光诱导信号的完整动力学过程。使用单个脉冲不会改变纳米粒子对后续脉冲的光学特性，从而可以实现可靠的时空分布映射。

此外，研究人员发现粒子的生成和生长源于前驱物。本质上，作为一种成像方式，fsLS-CUP提供了超快2D诊断，有助于从根本上理解纳米粒子的生成，并促进其在材料科学和生物医学工程等不同领域的广泛应用。

据悉，在环境科学、燃烧科学和材料科学领域，烃类火焰中碳纳米粒子的生成及其动力学特性仍存在争议。

附：英文原文

Title: Single-pulse ultrafast real-time simultaneous planar imaging of femtosecond laser-nanoparticle dynamics in flames

Author: Mishra, Yogeshwar Nath, Wang, Peng, Bauer, Florian J., Gudipati, Murthy S., Wang, Lihong V.

Issue&Volume: 2024-08-29

Abstract: The creation of carbonaceous nanoparticles and their dynamics in hydrocarbon flames are still debated in environmental, combustion, and material sciences. In this study, we introduce single-pulse femtosecond laser sheet-compressed ultrafast photography (fsLS-CUP), an ultrafast imaging technique specifically designed to shed light on and capture ultrafast dynamics stemming from interactions between femtosecond lasers and nanoparticles in flames in a single-shot. fsLS-CUP enables the first-time real-time billion frames-per-second (Gfps) simultaneous two-dimensional (2D) imaging of laser-induced fluorescence (LIF) and laser-induced heating (LIH) that are originated from polycyclic aromatic hydrocarbons (PAHs) and soot particles, respectively. Furthermore, fsLS-CUP provides the real-time spatiotemporal map of femtosecond laser-soot interaction as elastic light scattering (ELS) at an astonishing 250 Gfps. In contrast to existing single-shot ultrafast imaging approaches, which are limited to millions of frames per second only and require multiple laser pulses, our method employs only a single pulse and captures the entire dynamics of laser-induced signals at hundreds of Gfps. Using a single pulse does not change the optical properties of nanoparticles for a following pulse, thus allowing reliable spatiotemporal mapping. Moreover, we found that particle inception and growth are derived from precursors. In essence, as an imaging modality, fsLS-CUP offers ultrafast 2D diagnostics, contributing to the fundamental understanding of nanoparticle’s inception and broader applications across different fields, such as material science and biomedical engineering.

DOI: 10.1038/s41377-024-01588-x

Source: https://www.nature.com/articles/s41377-024-01588-x