Investigation of the effect of target water content on a laser-induced plasma

Because of difficulties with matrix matching in a number of laser solid sampling techniques, plasma diagnostics are often employed directly or indirectly (through internal standardization) as a means of generating working curves. In this study, the effects of water content of CaCO₃ powder on size, shape, excitation temperature, electron number density, continuum emission, and line emission of plasmas generated on the powder are investigated. Although the specific wetting properties of the matrix will determine the magnitude of the water content effects, the observations made for CaCO₃ powder indicate that emission and electron number density are the two parameters affected significantly by water content, both decreasing with increasing weight % water. In laser-induced breakdown spectroscopy of samples that may have an inhomogeneous distribution of water or of samples in which water content can vary significantly, accounting for the effects of this water is essential to an accurate analysis.