Effect of metals and surface contaminants on the decoration of graphite

Existence of microdroplets and dispersed atoms on the graphite surface in electrothermal atomizers

“…The Au aggregates form at preferential locations on the graphite surface (e.g., bottom of surface steps or adsorbed gas impurities) and droplet growth occurs by collision of the mobile Au atoms on the surface with the less mobile Au droplet. Electron micrographs by Baird et al (25) of vacuum-deposited Ag on graphite show similar droplet formation with droplet diameters as small as 5 nm. Thus, the precedence for the existence of well-defined microdroplets on graphite has been established.…”

“…Interestingly if (4-40) X 104 spheres of 30-nm radius existed for the above sample range, Ka would equal 10 (free molecule regime). The size range is not unreasonable in light of the work by Baird et al with Ag (25). However, the rate of evaporation of a droplet proportional to the surface area of the droplet (eq 8) and a 2/3 order release would be expected.…”

Topology and vaporization characteristics of palladium, cobalt, manganese, indium, and aluminum on a graphite surface using electrothermal atomic absorption

“…distribution the total release of the analyte occurs over a shorter time period during the atomization cycle. Transmission electron microscopy of vapor-deposited Pd on thin layers of crystalline graphite also has revealed the presence of Pd droplets (16). However, the geometry of analytical amounts of Pd in GFAA during vaporization has not been elucidated previously.…”