Mass spectrometry utilizing collisional ionization of cesium: Maleic anhydride and succinic anhydride

Abstract

The translational energy dependence of the relative cross section for production of negative ions by collisions of fast cesium atoms with maleic anhydride (C₄H₂O₃) and succinic anhydride (C₄H₄O₃) has been studied from threshold up to approximately 20 eV (c.m.). Accurate measurements of the threshold energy for the creation of Cs⁺ and ${\mathrm{C}}_4{\mathrm{H}}_2{\mathrm{O}}_3^{-}$ from collisions of cesium atoms with maleic anhydride yield the electron affinity of maleic anhydride to be 1.4±0.2 eV. A number of fragment negative ions are observed from both compounds and the results are compared with our recently reported electron impact studies. ${\mathrm{CO}}_2^{\mathrm{-*}}$ ions are observed to be unstable with respect to autodetachment, and the autodetachment lifetimes are measured to be 62±10 and 71±10 μsec for ${\mathrm{CO}}_2^{\mathrm{-*}}$ from maleic and succinic anhydride, respectively. In both cases the lifetime of ${\mathrm{CO}}_2^{\mathrm{-*}}$ is independent of the collision energy from threshold up to 15 eV.