A synchrotron photoionization mass spectrometric study on plasma-assisted propanol oxidation in a nanosecond discharge

The oxidation kinetics of propanol isomers under nanosecond pulsed dielectric barrier discharge (DBD) conditions were investigated using a combination of flow-tube plasma experiments and numerical simulations. Species identification and quantification were performed via synchrotron photoionization molecular beam mass spectrometry (PI-MBMS), which effectively minimizing post-sampling collisions and maximizing retention of active components. This technique enabled the detection of both stable molecules and reactive species, including ions, radicals, and excited states. Photoionization efficiency (PIE) spectra and ionization energy data facilitate qualitative identification, while quantitative analysis is performed by integration of ion signals and ionization cross sections. Intermediates such as CH₂O, CH₃CHO, C₂H₅CHO, CH₂CO, C₃H₅OH, C₂H₄, C₃H₆, CH₃OH, and C₂H₅OH in the present system were experimentally determined for the first time. A reaction kinetic model was developed and validated against experimental results. Rate-of-production (ROP) analysis revealed the dominant reaction pathways for the consumption of n-propanol and iso-propanol, as well as the formation of key intermediates and products.