Effect of mass spectrometric sampling interface on the fundamental parameters of an inductively coupled plasma as a function of its operating conditions: Part I. Applied r.f. power and vacuum

The effects of a mass-spectrometer sampling interface on the fundamental parameters of an argon inductively coupled plasma were studied. Laser-scattering techniques were used to obtain radially resolved values for electron number density (ne), electron temperature (Te), and gas-kinetic temperature (Tg) of the ICP upstream from the sampler as a function of applied r.f. power while different sample solutions were introduced. In addition, radially resolved calcium ion and atom number densities were determined under the same conditions in order to study the effects of matrix elements upstream from the mass spectrometer interface. It was found that the interface causes changes in the fundamental parameters that are dependent on the ICP applied r.f. power and the pressure at the back of the sampling interface. Furthermore, the changes caused by matrix interferents are different in the presence and in the absence of the sampler.