Experiments with TT can also help to understand gold VS atomization
when taking into account hydride atomization mechanism in this
atomizer: a cloud of H radicals, filling only a small portion of the volume
of the atomizer, is formed at the beginning of the hot zone of the atomizer
by reactions between hydrogen and traces of oxygen (always present
in sample, reagent solutions and gases) [4]. Hydrides are, under
optimum conditions, fully atomized in the cloud by reactions with H
radicals analogously as in the case of FIGS atomizer even though the
density of H radicals in the cloud is much lower than in FIGS [4]. Analogously
as in the case of DF and FIGS, the relatively intensive gold signal
(Fig. 8) does not correspond to thermodynamic equilibrium calculations:
fraction of gold free atoms at the actual temperature of 900 °C
should be negligible (Fig. 9). This indicates an equal mechanism as for
hydrides: atomization of the nanoparticles in the cloud of H radicals situated
at beginning of the hot zone of the atomizer. It should be
highlightedmuch higher sensitivity is observed in TT than in FIGS (compare
Figs. 8 and 5) even though FIGS produces much higher H radical
density than TT [4]. This again points to the key role of temperature in
volatilization/atomization of the nanoparticles: the higher temperature
in TT compared to FIGS can accelerate vaporization of nanoparticles in
the form of AuH and, subsequently, AuH can be atomized much faster
in the H radical cloud than in “low-temperature” FIGS.