Laser Induced Breakdown Spectroscopy
LIBS is a
technology which involves laser-based optical emission spectrometry to analyze elemental composition of various materials. It dates from 1962, when it
has first been shown to work with ruby laser. In 1980 Leon
Cremers et al. from Los Alamos National Laboratory (New Mexico, USA), were first to develop this practical application of Laser optical emission spectrometry; this group suggested the acronym LIBS.
In a nutshell, LIBS is a kind of spectroscopy where a pulse laser serves as an excitation source.
LIBS operates by focusing the laser
Nd:YAG) onto a small area at the surface of the specimen; the length of the impulse is around 10 nanoseconds, while the power density at the surface can reach 1 GW/cm2, which raises the temperature at the focus above 30000
oC, ablates a very small portion of the material, in the range of
picograms, instantaneously generating plasma. Plasma is an electroneutral combination of atoms, ions and electrons. When these excited ions recombine with electrons, recreating atoms of the analyzed substance
in a low energy state, photons are emitted. Characteristic atomic emission lines of the elements, with wavelength in 190-1100 nm range,
can be observed.
Using an optical system, the emission
is directed into a sensitive CCD spectrometer, which simultaneously detects the representative lines of all the elements present in the analyzed substance. The resulting optical spectrum is characteristic of the given substance. The line intensity of each element
is correlated with its concentration in the analyzed material.
The optical range is quite wide; it is thus possible to select non-interfering lines for the chemical elements of interest, including light elements (B, C, Si, Al, P...). This is why LIBS can be applied for all kinds of