Enclosed Inductively Coupled Plasma: Spatially Resolved Profiles of Rotational Temperatures and Analyte Atom Distribution

Abstract

In order to investigate evaporation and desolvation capacities of the enclosed inductively coupled plasma discharge, rotational temperatures (which are commonly considered a good approximation of the heavy particle temperature or gas temperature) were determined as a function of their spatial distribution and their dependence on physical parameters such as gas flows (80–740 mL/min), moisture load, etc. The procedure utilizes the fine structure of the (A²Σ⁺ → X²Π_i) OH band having its band head at 306.4 nm. The rotational temperatures were obtained from the slopes of their Boltzmann plots. Spatial resolution and simultaneous line detection was possible by using a charge-coupled device (CCD) camera in the focal plane of the removed exit slit of a Czerny–Turner monochromator. An interactive data language (IDL) program was developed to calculate the temperature distribution from the received CCD images. Results of the measurement show that the rotational temperatures are between 3750 and 4350 K. They further show the M-shaped spatial profile of analyte intensities and temperature. In the examined gas flow range (80–740 mL/min) the dependence on absolute gas flows and moisture load (5 mg/L) is negligible.