AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Development of a Triggering-LIBS for Determination of Elemental Composition of Single Particles in Real Time
HEESUNG LEE, Jihyun Kwak, Gibaek Kim, Kihong Park, Gwangju Institute of Science and Technology
Abstract Number: 38 Working Group: Instrumentation and Methods
Abstract The Laser Induced Breakdown Spectroscopy (LIBS) with an aerosol focusing system has been developed to detect the elemental composition of single particles in real time. The LIBS uses a powerful laser focused by the focusing lens, which generates a micro-plasma to dissociate sampled particles to the atoms or ions at the atmospheric pressure. When the excited species go back to its ground state, the specific emission lights appeared depending on their elemental constituents. The distinguishable emission lines were then transferred into a broadband spectrometer, and the LIBS spectra are analyzed for the identification of the elements and their quantification.
The LIBS has been utilized to measure the temporal behavior of heavy metals in the period of Asian Dust or specific particle events in our previous studies (Park et al., 2009; Park et al., 2012). The studies showed significant inspiration for the time resolved properties of the particles. Nevertheless, a single particle detection had not yet been fully accomplished because of the low hitting efficiency of particles by the free-firing laser at atmospheric level of concentration.
In this study, we used a continuous wave laser (642nm, 35mW, Excelsior Laser, Spectra Physics Inc., USA) to find the exact transit time for a single particle to arrive at the focal point of the following pulsed laser and to trigger that second Nd:YAG laser (1064nm, 155mJ/pulse, Surelite II-10, Continuum Inc., USA) which produces a micro-plasma, leading to the enhancement of the hitting ratio of particles by the combination of two lasers. By using various particles of size, composition, and number density, the triggering-LIBS was evaluated. Data show that the particle hitting efficiency of the triggering-LIBS can significantly be evaluated, enhanced compared to that of the free-firing LIBS system.