10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

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Development of a Laser-Induced Breakdown Spectroscopy (LIBS) System with Timed Ablation for a Single Particle Detection at a Low Concentration

HYUNOK MAENG, Hoseung Chae, Heesung Lee, Gibaek Kim, Haebum Lee, Kyoungtae Kim, Jihyun Kwak, Gangnam Cho, Kihong Park, Gwangju Institute of Science and Technololgy

     Abstract Number: 313
     Working Group: Instrumentation

Abstract
The atmospheric aerosols are of current interest because of their effects on visibility impairment, human health and climate change. Especially, the chemical components of aerosols are essential to find their formation mechanisms. The elemental composition of aerosols has been commonly analyzed using filter based methods such as inductively coupled plasma-mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS). Although these are well established techniques, they typically require a long sampling time (12-24 hours) and a series of sample pre-treatments. Also, there are not suitable for the detection of elemental variation among particles and their mixing state. In this study, the laser-induced breakdown spectroscopy (LIBS) technique was applied for the real-time detection of the elemental composition of a single particle because of its rapid detection capability. In addition, a LIBS system with timed ablation was developed by employing a continuous wave (CW) laser in front of the pulse laser to improve the low hitting efficiency (%) and hitting rate (hits/min) of single particle. This system was evaluated using laboratory-generated particles (CaCl2, MgCl2, NaCl and KCl) at various sizes (200-600 nm) and number concentration (50-100,000 particle/cm3) range. Results showed the hitting efficiency (%) of 300-400 nm particles with a concentration of 50 particles/cm3 was increased up to 80%. Also, in case of 200 nm particles, the lower detection limit (<50 particles/cm3) was achieved compared to those obtained under the constant firing mode of pulse laser. Furthermore, the hitting rate (hits/min) sharply increased around 150 times. Lastly, results of the evaluation for the real-time detection of the mixing state of particles composed of various elements will be presented in this study.