Analysis of flame structure by molecular-beam mass spectrometry using electron-impact and synchrotron-photon ionization

Molecular-beam mass spectrometry (MBMS) has proven to be a powerful tool for the general analysis of flame structure, providing concentrations of radical and stable species for low-pressure flat flames since the work of Homann and Wagner in the 1960’s. In this paper, we will describe complementary measurements using electron-impact ionization with a high-mass-resolution quadrupole mass spectrometer and vacuum-ultraviolet photoionization in a time-of-flight mass spectrometer. Isomers are resolved that have not been separately detectable before in MBMS studies of flames, including C$_3$H$_2$, C$_3$H$_4$, C$_4$H$_3$, C$_4$H$_4$, C$_4$H$_5$, C$_6$H$_6$, and C$_2$H$_4$O. The qualitative and quantitative results of MBMS have led to advances in modeling and applying flame chemistry.