AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Development of a Laser-Induced Breakdown Spectroscopy (LIBS) System with Timed Ablation to Increase Detection Efficiency of a Single Particle
HYUNOK MAENG, Hoseung Chae, Heesung Lee, Gibaek Kim, Haebum Lee, Kyoungtae Kim, Jihyun Kwak, Gangnam Cho, Kihong Park, Gwangju Institute of Scinece and Technology(GIST)
Abstract Number: 476 Working Group: Aerosol Chemistry
Abstract Elemental composition of ambient aerosols has been commonly determined using filter-based techniques such as atomic absorption spectroscopy (AAS) and inductively coupled plasma-mass spectrometry (ICP-MS). However, these techniques usually require a long sampling time (12-24 hours) and a series of sample pre-treatments. In addition, elemental variation among particles and their mixing state cannot be determined by filter-based method. On the other hand, the laser-induced breakdown spectroscopy (LIBS) technique can be used to determine elemental composition in real-time because it is a useful tool for the rapid detection. However, hitting efficiency (%) and hitting rate (hits/min) are significantly low under the constant firing mode of pulse laser when particle concentration is low. Thus, this study focused on developing the LIBS system with timed ablation to improve detection efficiency of a single particle by employing a continuous wave (CW) laser in front of the pulse laser as a trigger source. The evaluation of this system was conducted using laboratory-generated particles (CaCl2, MgCl2, NaCl and KCl) at various sizes (200-600 nm) and number concentration (100-100,000 particle/cm3) range. As a result, hitting efficiency (%) was improved significantly by more than 26 times at 1,000 particles/cm3. Lower detection limits, in terms of particle size (~200 nm) and number concentration (<100 particles/cm3), were also achieved compared to those obtained under the constant firing mode of pulse laser. Lastly, the hitting rate (hits/min) increased around 15 times. In conclusion, this study suggests that the developed LIBS system with timed ablation significantly improves the determination of elemental composition of a single particle under low concentration in real-time.