LIBS for Geological Applications – Laser Induced Breakdown Spectroscopy

Laser Induced Breakdown Spectroscopy or LIBS is a high speed optical emission technique that can be applied to geological materials such as drill core, RC chips etc. It produced elemental analyses and can detect every element in the periodic table with a sensitivity better than ppm.

At the AMI we use ELEMISSION LIBS systems that can scan at a rate of 1300 points per second with tailorable scan areas and times, depending on your requirements.

How Does LIBS Work?

A pulsed laser is focused on the surface of a sample. The energy from the focused laser produces a small plasma cloud. As the plasma collapses, photons are emitted.

This emitted (photons) light is analysed by an optical spectrometer which measures the intensities and wavelengths. Every element has a unique combination of spectral peaks, and these are used to determine the composition of each spot analysed, while the intensity is directly proportional to concentration.

Schematic of LIBS for geological applications

The spatial distribution of these analysis points is user defined between 35 µm and 500 µm, producing a wide range of resolution and scan time/area options. This provides the user with the flexibility to perform large area screening scans to identify specific regions of interest for more concentrated analysis.

LIBS for Automated Mineralogy

Using a database of typical spectra, each spot measured by LIBS can be related back to a single mineralogical phase. By shooting a large number of spots, mapping or microanalysis of the sample can be performed, revealing mineral distributions and concentrations. The image below compares LIBS analysis to analysis via Scanning Electron Microscopy and Energy Dispersive Spectroscopy (SEM/EDS), a well-accepted automated mineralogy technique.

LIBS validation - comparing data to TIMA for geological samples

As can be seen, the mineralogical analyses are very similar. However, the LIBS analysis can be completed in a fraction of the time. Furthermore, it is also possible to measure as-received samples, using LIBS, resulting in further workflow efficiencies.

LIBS vs. XRF

LIBS produces elemental data similar to XRF but with from smaller spot sizes enabling mapping of geological materials such as drill core with high degrees of accuracy. Most importantly, LIBS is suitable for every element in the periodic table, making it the superior solution for those involved in lithium exploration and mining. Another key advantage of LIBS is there is little to no sample preparation required and the data can be collected in situ.