AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Development of Triggering-LIBS for Elemental Analysis of Submicrometer Single Particle in Real Time
Heesung Lee, GIBAEK KIM, Jihyun Kwak, Kihong Park, GIST
Abstract Number: 167 Working Group: Instrumentation and Methods
Abstract Atmospheric aerosols play important roles in radiation balance, cloud formation, visibility impairment, and human health. Although PM10 or PM2.5 contain small fractions of heavy metals, the exceeding amounts of toxic heavy metals could cause adverse effects on human health. In order to measure the heavy metal concentration, conventional filter–based techniques have been used, in which the collected ambient particles on a filter for 12 or 24 hours were extracted into a solution with subsequent analysis using Inductively Coupled Plasma–Mass Spectrometry (ICP-MS) or Atomic Absorption Spectroscopy (AAS). Nevertheless, the complex preparation steps resulted in various sampling artifacts, and the methods suffered from a low time resolution.
The Laser Induced Breakdown Spectroscopy (LIBS), used to determine elemental composition of particles in real time (Kwak et al., 2012; Kim et al., 2013), employed laser–induced plasma to dissociate and break particles in that plasma volume. The particles were turned into their plasma state and when they came to the ground state, unique lights were produced according to their atomic constituents.
The previous version of our LIBS system employed an aerosol–focusing system to hit particles by laser in a more conditional manner. Due to the free firing laser system, the previous system suffered from low hitting efficiency. In current study, we employed a triggering laser system to hit submicrometer particles with higher efficiency than that of conventional LIBS systems (i.e., free firing LIBS system). The Nd:YAG laser was used as a plasma source. The triggering signal was generated when the particles passed through a continuous wave (CW) laser beam (642 nm, Excelsior Co.), and the signal was sent to an oscilloscope (Lecroy Co.) through photomultiplier tube (PMT) (H10722-20, Hamamatsu Co.). A delay generator (BNC 575, BNC Co.) controlled the firing of flash lamp, Q–switch of pulse laser (1064nm, Surelite II-10, Continuum Co.), and a gate delay of a spectrometer (Applied Spectra Co.). This enabled the pulse laser to fire at the time when the particles arrived at a focal point of the laser beam.