Progress in Fixed-Photon-Energy Time-Efficient Double Imaging Photoelectron/Photoion Coincidence Measurements in Quantitative Flame Analysis

Abstract - Photoelectron photoion coincidence (PEPICO) spectroscopy as an attractive new technique for combustion analysis was used in a fixed-photon-energy configuration to provide quantitative species profiles in laminar premixed flames. While such measurements are conventionally performed with molecular-beam mass spectrometry (MBMS) using electron ionization (EI) or vacuum ultraviolet (VUV) photoionization (PI) with synchrotron radiation, these techniques have some limitations. The possibility to record photoelectron spectra (PES) simultaneously with photoionization data, providing fingerprint information for reliable species identification, presents a significant advantage of PEPICO spectroscopy especially in complex reactive mixtures. The multiplex approach presented here, enhanced by the imaging capabilities of the electron and ion detection in the so-called double-imaging PEPICO scheme (i 2 PEPICO), provides, in different experimental situations, an unprecedentedly detailed combustion analysis regarding both species identification and quantification. Problems and perspectives of the present fixed-photon-energy PEPICO approach will be discussed.