ABSTRACT
LIBS is the acronym for “laser-induced breakdown spectroscopy,” and it is also called LIPS (laser-induced plasma spectroscopy) and other related names.[4.1] The principle behind LIBS is illustrated in Figure 4.1. In the LIBS process, a laser beam is focused onto a small area, producing hot plasma. The material contained in plasma is atomized, and light is released corresponding to a unique wavelength for each element. Despite the fact that the processes involved are complex, the emission intensity from the atomized species can be described by the following equation with the assumption of a uniform plasma temperature:
I n K g E kTi i i j i j i j
(4.1)
In the above expression, I(i) is the emission intensity of species i, n(i) the concentration of species i, K(i),j a variable that includes the Einstein A coef-—cient from the upper energy level j, g(i),j the statistical weight of species i at the upper energy level j, E(i).j the upper energy level of species i, k the Boltzmann constant, and T the plasma temperature. In Equation (4.1), there are several factors that affect the emission intensity I(i). These include plasma temperature, plasma nonuniformity, and matrix effects. The appropriate correction factors must be included in K(i),j to obtain quantitative results.
