Abstract by Daniel Thurston
Chemistry and Biochemistry
Using Absorption and Emission Imaging to Measure the Spatial Distribution of Key Excited Species in a Dielectric Barrier Discharge
Helium metastable atoms are among the key energetic species in plasma-based ambient desorption/ionization (ADI) sources, and an understanding of where and when they are produced is essential in developing an effective model of how ADI sources function. We are producing time- and space-resolved maps of He metastable atom densities, as well as other excited species including N2, N2+, and O in a miniature dielectric barrier discharge used as an ADI source. For emission measurements, the discharge is mounted in front of a spectrograph with an intensified gated charge coupled device (CCD) as a detector. The gated detector records time- and space-resolved emission intensities. For He metastable absorbance measurements, laser light at 1083 nm is focused through the plasma and into a detector. The combined emission and absorbance and emission data map the spatial distributions of key species in the plasma. These measurements of key energetic species will be used to develop a more accurate model for the behavior of ADI sources. The model will serve as a basis for the development of improved sources.