Research Group Inorganic Trace Analysis

Laser-Induced Breakdown Spectroscopy (LIBS)

The principle of LIBS is based on focusing a high-energy (GW/cm2) pulsed laser on a sample surface. The laser pulse ablates material from the sample and a laser-induced plasma is formed. In this plasma, the previously ablated material is partly atomized, ionized, and excited. When the excited states decay, element-specific radiation is emitted. Using a collection optic, light emitted from the plasma is collected, separated by the wavelength using a polychromator, and detected using a CCD camera. With LIBS spectra containing large amounts of information (1 hour of LIBS analysis typically generates several GBs of data), machine learning and other chemometric tools are often used for data analysis  (Figure 1).

 

The principle of LIBS is based on focusing a high-energy (GW/cm2) pulsed laser on a sample surface. The laser pulse ablates material from the sample and a laser-induced plasma is formed. In this plasma, the previously ablated material is partly atomized, ionized, and excited. When the excited states decay, element-specific radiation is emitted. Using a collection optic, light emitted from the plasma is collected, separated by the wavelength using a polychromator, and detected using a CCD camera. With LIBS spectra containing large amounts of information (1 hour of LIBS analysis typically generates several GBs of data), machine learning and other chemometric tools are often used for data analysis.

© Lukas Brunnbauer

LIBS

Figure 1. Schematic representation of LIBS

LIBS provides several characteristics which makes it a unique technique in the field of direct-solid sampling elemental analysis:

  • LIBS can detect all elements of the periodic table.

  • LIBS provides detection limits ranging from the µg/g level for alkaline and earth alkaline metals to the per mille range for non-metals.

  • LIBS offers simultaneous multi-element analysis making it an excellent tool for non-targeted analysis which is especially useful if no previous information about a sample is available. Additionally, multi-element analysis is very useful for sample classification, identification, or discrimination based on an elemental fingerprint. This is of great interest in many different fields such as materials science, forensics, life-science or environmental analysis.

  • LIBS can provide spatially resolved information with a lateral resolution in the 50-200 µm range and a depth resolution in the low µm range. Therefore, it is an excellent tool for the fast mapping of large sample areas (up to several cm2) and analysis of layered samples with thicknesses up to several mm.

  • LIBS can be operated in a stand-off configuration enabling analysis at a distance of several meters.