Transients in Rapid Reactions by Combined Molecular Beam and Mass Spectrometric Analysis

摘要

When using a mass spectrometer to monitor free radical and atom intermediates in rapid gas-phase reactions, identification of species is made difficult by the multitude of fragmentation processes that can occur during ionization. Our approach to this problem is to characterize the neutrals in a molecular beam before they enter the ionization region of the mass spectrometer. Thus, the trajectory of a species in an inhomogeneous magnetic field shows whether or not it has a large magnetic moment characteristic of a free radical; its motion in an inhomogeneous electric field indicates the magnitude of its electric dipole moment; and its velocity distribution determines its mass when the source temperature is known. This report describes the apparatus that we have constructed for this new technique and our initial experience with the method. Preliminary results on the electric discharge afterglow of SO2 are also discussed. (Author)