Figure shows aromatic products in the
Details of the experimental and data reduction procedures are sufficiently described in the literature , , ,  and  and are not repeated here. In short, we used a quartz probe and a differentially pumped vacuum system to sample gases from within the three different flames and then used a quasi-continuous beam of synchrotron-generated vacuum-ultraviolet (VUV) photons in the saha histone range of 8–17 eV as means to effectively ionize the sampled flame constituents. In a first step, we scanned the photon energy at a fixed burner position, which allowed us to record so-called photoionization efficiency (PIE) curves which were used to identify most of the compounds based on their characteristic ionization energies and PIE curves. While this is a very powerful technique, we have to keep in mind that especially for larger m/z ratios, this approach can become very complicated when potentially more isomers need to be separated and their ionization energies and PIE curves are unknown , ,  and .