Nanoparticle generation and its time evolution in laser ablation in liquids by observing the fluorescence images from nanoparticles

Research Project

Project/Area Number	17K06076
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Production engineering/Processing studies
Research Institution	Fukuoka Institute of Technology (2018-2019) Nagaoka University of Technology (2017)
Principal Investigator	Yamagishi Rie 福岡工業大学, 工学部, 准教授 (70432101)
Project Period (FY)	2017-04-01 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000) Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000) Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000) Fiscal Year 2017: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
Keywords	液中レーザーアブレーション / ナノ粒子 / 発光 / 可視化 / レーザーアブレーション / 蛍光ナノ粒子
Outline of Final Research Achievements	Videography imaging of UV-induced photoluminescence from YVO4:Eu3+ nanoparticles in laser ablation in liquid can visualize generation and evolution of them. A mist-like image growing from the target surface after the laser irradiation is observed and spread inside the first bubble until it reached its maximum size. The mist forms a triangular shape when the bubbles began to shrink. We think this mist presents fluorescence from the nanoparticles formed from the target by laser ablation. The shadowgraph and photoluminescence images indicated that the nanoparticles are restricted within the bubble during both the expansion and shrinkage phases. When the second bubble generated after the collapse of the first bubble expands and shrinks, the photoluminescence become thinner as the bubble expands and become thicker as it shrinks. This suggest that the nanoparticles derived from YVO4:Eu3+ target exist inside the bubble and remain within the bubble during its cycle of expansion and shrink.
Academic Significance and Societal Importance of the Research Achievements	液中レーザーアブレーションによるナノ粒子生成法において、生成する粒子の粒径分布や形態をコントロールするためには、粒子は、いつ、どこで、生成するのかについて把握することが重要であり、近年、その生成メカニズムの解明に関心が集まっている。本研究では、紫外光を当てると発光するYVO4:Eu3+タブレットを試料に用いて、マイクロ秒オーダーの高速度で動的にその過程を可視化した。粒子からの発光を高速度撮影することにより、蛍光ナノ粒子が形成されるタイミングの特定や微粒子の空間分布とその時間変化を明らかにすることができ、ナノ粒子の生成メカニズムの追究に有用な情報を提示することができた。