LIBS - A detection technique for material characterization
Laser-induced breakdown spectroscopy (LIBS) is a technique used routinely for the analysis of the elemental composition of materials.
LIBS is relatively simple to use and allows for rapid, real-time analysis. A pulsed laser is focused down to a high intensity spot on the material where it produces a short-lived high temperature micro-plasma or 'spark' which produces copious amounts of light emission. The atomic line emissions from such plasmas facilitates the identification of the elements within the material. The main components of a LIBS setup includes a pulsed laser, typically an Nd-YAG 1064 nm laser, a spectrograph such as Shamrock 500i with an ICCD, such as iStar DH340T-18U-03, as well as focusing and collection optics and software for control and analysis. LIBS systems can be configured for both the laboratory environment or in the field, including 'standoff' configurations when working with hazardous materials or in challenging environments.
A key challenge when acquiring 'clean' atomic emission spectra is the rejection of the extremely bright broadband emission which occurs during and just after the laser interaction with the target. Figure 1 shows a series of spectra and images of the plasma captured with varying delay relative to the laser pulse after interaction with a copper target e.g. a 2 pence coin. The early dominance of the broadband emission and the emergence of the atomic emission lines later in time is evident, hence the necessity to control the delay on the order of 10's of ns. Gatewidth of the ICCD was chosen to be 20 ns.