Chapter 1: LIBS Imaging fundamentals

1.1. LIBS

In Laser-Induced Breakdown Spectroscopy or Laser Spark Spectroscopy we use laser to make a spark on the sample, collect the light of the spark to a spectrometer, which disperses the light into its different wavelengths i.e colors and measures how much of each there is.

This is an atomic emission spectrum of the sample which reveals us how much of each element was in the spark made from the sample.

Terminology

Note on terminology, I will be using both Laser-Induced Breakdown Spectroscopy abbreviated LIBS and *aser Spark Spectroscopy as synonyms to refer to the same thing. The reaso using multiple terms for the same thing is that the established most common term for the technique is laser-induced breakdown spectroscopy, but a better term for understanding what happens is laser spark spectroscopy . In laser spark spectroscopy a laser is used to make spark which is measured with a spectroscope. Adding "induced" adds no value and "breakdown" is, in general speak, a more ambiguous and difficult to understand term than "spark". So when explaining it I prefer to call it laser spark spectroscopy. In Finnish I prefer the term laserplasmaspektroskopia but use also laserkipinäspektroskopia to clarify.

History

Atomic emission spectroscopy

Atomic emission spectroscopy has a long history. The color of flames has been used as an indicator for smelting of ores for millenia and flame and spark spectra was identified and described as being characteristic to specific substances in the 1800s by Talbot(1826) and Whetstone(1835). Dawson, J.B. (1991) ‘Viewpoint—analytical atomic spectroscopy: learning from its past’, J. Anal. At. Spectrom., 6(2), pp. 93–98. Available at: https://doi.org/10.1039/JA9910600093. .

1.2 LIBS Imaging

Imaging or scanning with LIBS means taking many measurements over an area to form an image. Many can mean thousands to millions of measurement points per image. Most common way to take the measurements is in a regularly spaced grid. The results is a spectral cube of spectral measurements for each position coordinate.