Design Of A Reflectron Time-of-flight Mass Spectrometer And Experimental Study Of Dissociative Electron Attachment To OCS

Time-of-flight mass spectrometer has been an important tool of modern physics and chemistry. The reflectron TOFMS has higher mass resolution than the linear TOFMS, so we designed a reflectron TOFMS. This mass spectrometer can be used for complex dissociative electron attachment reactions. And we introduce the principle and parameters of our reflectron TOFMS.Dissociative electron attachment (DEA) is a typical process occurring at low energy, with yields of the neutral and anionic fragments. We can get the details about DEA dynamics from the cross section, kinetic energy distribution and angular distribution of the anionic fragments measured in the experiments and the theoretical study.Dissociative electron attachments to OCS with the attachment energies of 4.3,4.7, 5.0,6.2,6.5,6.8,7.0 and 7.5eV are investigated by measuring the S momentum distributions with time-sliced anion velocity image mapping technique. In this energy range, the ground-state fragmentation, e-+OCS â†' CO (X1∑)+S-(Pu), is only one dissociation pathway allowed in energy. All velocity images show the predominant feature of the low-speed S ions, but the middle-and high-speed S ions appear at the higher attachment energies (6.2-7.5 eV). The trimodal speed distribution of S ion should be attributed to the different populations of the rovibrational states of CO fragment, however, the dynamic details of above dissociations are still unclear and demand theoretical calculations.