Time-gated resonance schlieren studies of analyte distribution in a graphite furnace atomiser

Abstract

A time-gated resonance schlieren system has been used to observe the distribution of analyte in the furnace during the course of atomisation in graphite furnace atomic absorption spectrometry. The system is a simple one lens schlieren configuration using a pulsed dye laser tunable near the resonance wavelength of the analyte as its source and a modified 35-mm camera for image recording. It is capable of producing a series of schlieren photographs from a single firing of the atomiser. Experimental results for the atomisation of sodium suggest the existence of sodium atom concentration gradients within the furnace. For a time during atomisation, sodium atom density is lower near the furnace wall than in the centre of the furnace. It is postulated that the observed gradients are due to a strong interaction of the atomic sodium with the graphite. The gradient arises as atomic sodium, generated within the furnace through a gas phase dissociation mechanism, is adsorbed on to the furnace wall.