Atomization of arsenic hydride in a planar dielectric barrier discharge: Behavior of As atoms studied by temporally and spatially resolved optical emission spectrometry

The excitation mechanism of arsenic atoms in a planar shaped dielectric barrier discharge (DBD) atomizer with sputtered grid shaped electrodes was studied by optical emission spectrometry (OES) with resolution in time and space. Due to the shape of the electrodes, the DBD design provides optical access to the plasma not only in end-on position but also in side-on direction. By means of an iCCD camera with nanosecond time resolution coupled to a monochromator it was shown that the spatial and temporal development of the plasma emission depends on the discharge gas nature (Ar, He). Applying argon, a dense and constricted plasma filament is formed, whereas in helium a much more homogeneous plasma is ignited. The impact of both plasmas on the emission signal of arsenic atoms was studied employing analyte introduction via hydride generation. The excitation of arsenic temporally follows the emission signal of helium or argon and is spread across the whole discharge volume. The basic discharge propagation dynamics showed similarities to previously presented results obtained by OES in a capillary DBD.