Development of laser-induced breakdown spectroscopy (LIBS) with timed ablation to improve detection efficiency. Issue 9 (2nd September 2017)

• Record Type: Journal Article
• Authors: Maeng, Hyunok; Chae, Hoseung; Lee, Heesung; Kim, Gibaek; Lee, Haebum; Kim, Kyoungtae; Kwak, Jihyun; Cho, Gangnam; Park, Kihong
• Is Part Of: Aerosol science and technology. Volume 51:Issue 9(2017)
• Page Start: 1009
• Page End: 1015
• Publication Date: 2017-09-02
• Subjects: Pramod Kulkarni; Aerosols -- Periodicals; Aerosol Propellants -- Periodicals; Aerosols -- Periodicals; 660.294515
• DOI: 10.1080/02786826.2017.1344352
• Languages: English
• ISSNs: 0278-6826

Abstract

ABSTRACT: A laser-induced breakdown spectrometer (LIBS) was developed for determining the elemental composition of individual airborne particles. The system employs two lasers focused on a narrow beam of particles. A continuous wave laser placed upstream scatters light from particles, while a pulse laser downstream ablates the particles. The scattered light from the upstream laser is used to trigger the downstream pulse laser, resulting in more accurate hitting of the particles than a free-firing laser system without the triggering signal (i.e., constant pulse laser firing). Various laboratory-generated aerosols (NaCl, MgCl2, KCl, and CaCl2 ) were used to evaluate the newly developed LIBS system. Particles were tightly focused into a center line with a sheath air focusing system using an optimum aerosol-to-sheath air velocity ratio. The locations of both the scattering laser and pulse laser beams were precisely controlled by a motorized X-Y stage controller. Data showed that for the LIBS with the triggering system, the hitting efficiency (%) of particles (200–600 nm) significantly increased (e.g., 350 nm particles had more than 26 times higher hitting efficiency at 1, 000 particles/cm 3 ), and much lower limits of particle size (∼200 nm) and number concentration (<100 particles/cm 3 ) were achieved compared to the free-firing laser condition. Additionally, the hitting rate (hits/min) significantly increased with the triggering system. Our results suggest that the LIBS with the triggering system can be useful for real-time detection of elements of particles existing at low number concentrations (e.g., atmospheric particles) and for the determination of the variation of elemental composition among particles. © 2017 American Association for Aerosol Research