Effect of gas pressure on the collisional line width and line shift in graphite furnace atomic absorption spectrometry

Abstract

The collisional line width of the resonance atomic absorption lines of Ca, Cu and In have been measured in graphite furnace atomisers by means of a wavelength modulated échelle spectrometer and a measurement method based on transmission profile fitting. A measurement precision of ±0.1 pm is observed for Cu (324.754 nm) based on growth curve shapes measured in peak area or peak height. Time resolved line widths within a single atomisation have been measured for Ca (422.673 nm) and for In (410.176 nm), with a time resolution of 0.3 s and a precision of ±0.5 pm. This measurement precision is sufficient to show clearly the effect of increased gas pressure on the line width and the line shift. Collisional cross-sections for In and Ca are estimated from the effect of pressure on the line widths and shifts and are compared with previously published values obtained using theoretical calculations.