Unexpected increases of atomic vapor temperature in graphite furnace AAS

Temperature increases of the atomic vapor in the presence of matrix modifiers were studied under different atomization conditions. In rapid atomization, the atomic vapor temperatures of Pb and In in the presence of Pd modifier were increased by 400degC compared with those in the absence of the modifier. These phenomena were not observed in slow atomization. The change of the free energy and the vaporization by an endothermic reaction due to a decrease in the activity coefficient of the analyte metal in the alloy were presumed to be the cause for the temperature increases. (author)