Effect of Operating Frequency on Spatial Features of the Inductively Coupled Plasma

Abstract

An unambiguous comparison has been made of the spatial features of a 27.12 and a 40.68 MH z inductively coupled plasma. Experiments were carried out with a switchable-frequency, solid-state radio-frequency generator from the Leco 2000 system. Several features of analytical signi cance have been evaluated in a spatially resolved fashion. Resu lts from optimization of the magnesium ionto-atom (M g II/Mg I) line-intensity ratio have been com pared. The volume of the two discharges was estimated from molecular nitrogen-ion emission, and a spatially resolved m ap of the Fe(I) excitation temperature was determined by means of a Boltzmann analysis at each spatial location. Calcium and magnesium ion-to-atom lineintensity ratios have been calculated throughout both plasmas. Finally, limits of detection are presented. The results indicate that the plasma operated at 40.68 MHz provides slightly better gures of merit, although fundamental parameters suggest a lower degree of analyte excitation. This difference is explained by examining the results of a simulation of plasmas operated at 27.12 and 40.68 M Hz.

Effect of the plasma operating frequency on the figures of merit of an inductively coupled plasma time-of-flight mass spectrometer

“…6 Consistently, a reduction in the Mg II : Mg I ratio, an indication of plasma robustness, was later reported at 40 MHz for the same experimental system. 7 As in the ICP-AES investigations, the effect of the operating frequency on the analytical characteristics of ICP-MS systems has also been evaluated. 1,2 Optimal nebulizer flow rates for 40 MHz systems are typically lower than those at 27 MHz, and the axial distributions of analyte and background ions are shifted to lower sampling depths in 27 MHz plasmas.…”

Advances in atomic emission, absorption and fluorescence spectrometry and related techniques

“…218 A spatial comparison has been made of ICPs operated at 27.12 and 40.68 MHz using a switchable-frequency generator. 219 The Mg II/Mg I ratio, Fe I T exc and discharge volume (from N 2 ion emission) were studied. After optimisation the authors concluded that slightly better figures of merit were obtained with the 40.68 MHz ICP.…”