EFFECT OF GAS-PRESSURE ON THE COLLISIONAL LINE-WIDTH AND LINE SHIFT IN GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY

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 echelle 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.