| The introduction of electrothermal atomizers with atomic absorption analysis (ETA-AA) using a pyrolytically coated graphite tube as a probe in determining the topology of analyte species during vaporization at submonolayer coverages and subsequent metal/graphite interactions under 1 atm of Ar has been presented. The acquisition of spatially resolved absorbance profiles allows the determination of the relative metal/graphite interactions within a graphite furnace. For relatively weak metal/graphite interactions, a model considering vaporization from aggregates is presented. A second model postulating the desorption of individual metal atoms from the graphite surface is used to explain those elements exhibiting relatively strong metal/graphite interactions.;The use of atmospheric pressure temperature-programmed thermal desorption (AP-TPD) varying the initial surface coverage of the analyte identifies the order of the release which can be related back to the geometry of the metal or metal oxide during vaporization. The energetics of release obtained for the various elements from Arrhenius plots probably represent the heat of desorption of metal atoms from the graphite surface or the enthalpy of vaporization of the metal microdroplets or the desorption at the edge of the metal/graphite interface for an island or hemisphere. Results from computer simulations varying the order of release are compared with experimental data.;The comparison of absorbance profiles from aerosol and manual deposition studies in which the initial particle size of the metal salt is varied provides confirmation of vaporization from aggregates or dispersed atoms from the graphite surface. Au, Cu, Ag, Pd, Co, Mn, In, and Al are the elements examined using the above three experimental methods.;Additional experiments were initiated with Cu, Au, and Ag in which extreme variations in the dry temperature (353-553 K) was employed in the evaporation of the aqueous solution droplet. The results are explained in light of the above two models. |
