Covariance mapping mass spectroscopy using a pulsed electron ionizing source: application to CF₄

Abstract

We report the implementation of covariance mapping mass spectmscopy to pulsedelectrowbeam ionization time-of-flight mass spectroscopy. The technique has been applied .~..

Electron ionization of CO2

“…As described above, to determine the ion detection efficiency (f i ) we recorded singles and pairs spectra of CF 4 at ionizing electron energies of 100 and 200 eV. Comparison of this data to the absolute cross-sections of Bruce and Bonham [39,40] resulted in a value of f i = 0.20 ± 0.01, in close agreement with previous determinations of f i for our apparatus [19,31,30].…”

“…To measure the ion detection efficiency f i separate experiments were performed, under the same voltage conditions employed in this study, to record the intensity of single ions and ion pairs formed by electron ionization of CF 4 . Comparison of this data to the corresponding absolute measurements of Bruce and Bonham [39,40] yields a value of f i , as has been described previously in the literature [37,31,30].…”

The formation of boron containing fragment ions from the ionization of BCl3

“…The resulting ion flight times from the TDC are then transferred to a memory module which, when full, is rapidly dumped to a PC. As discussed in previous publications [14,18], it has been confirmed experimentally that there are no mass discrimination effects occurring in this apparatus, ensuring that quantitative data can be extracted from the mass spectra [19,20].…”

An (e, 2e+ ion) study of electron-impact ionization and fragmentation of tetrafluoromethane at low energies

“…Electron impact studies include measurements on electron energy loss [33][34][35][36][37][38][39][40][41], excitation [42], ionization observing total [43,44], total dissociation [45] and partial ionization cross sections using fragment ion mass analysis [42,[46][47][48][49][50][51][52]. Furthermore, binary (e, 2e) studies [53,54] and electron impact fragment ion-photon coincidences (FIPCO) [55] were performed.…”