Combining Infrared transmission and Raman scattering for the fundamental study of CO2 plasma – active surface interaction

Non-thermal plasmas offer a low-energy method for CO2 dissociation, but controlling product selectivity is challenging. Preventing CO2 reformation from O and O2 is essential. Solutions like plasma catalysis and plasma-membrane coupling involve plasma-surface interactions, complicating chemical kinetics. Combining Raman spectroscopy and IR absorption spectroscopy allows the study of how oxygen atoms and vibrationally excited molecules interact with surfaces, including catalysts (CeO2) and membrane materials (YSZ). Raman scattering also serves as a thermometric method to measure surface temperature under direct plasma exposure, which is crucial for understanding surface mechanisms. This study uses a glow discharge of CO2 and O2 gas at low pressure (1-5 torr) with a discharge current of 10-50 mA. In situ Raman spectroscopy is performed using a pulsed laser on a material pellet. The scattered light spectrum provides time-resolved measurements of temperature and structural changes induced by gas and plasma exposure. The same pellets are examined with FTIR transmission to track carbonate formation on the surface. These combined results offer a comprehensive understanding of plasma-surface interaction mechanisms, vital for developing advanced catalyst and membrane materials.