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Absolute cross sections for electronic excitation of pyrimidine by electron impact

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2016
Author Regeta Khrystyna, Allan Michael, Mašín Zdeněk , Gorfinkiel Jimena D.,
Project Chemical and Physical Processes from Electron-Molecule Interactions
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Original article (peer-reviewed)

Journal Journal of Chemical Physics
Volume (Issue) 144
Page(s) 024302
Title of proceedings Journal of Chemical Physics
DOI 10.1063/1.4939077

Open Access


We measured differential cross sections for electron-impact electronic excitation of pyrimidine, both as a function of electron energy up to 18 eV, and of scattering angle up to 180◦. The emphasis of the present work is on recording detailed excitation functions revealing resonances in the excitation process. The differential cross sections were summed to obtain integral cross sections. These are compared to results of R-matrix calculations, which successfully reproduce both the magnitude of the cross section and the major resonant features. Comparison of the experiment to the calculated contributions of different symmetries to the integral cross section permitted assignment of several features to specific core-excited resonances. Comparison of the resonant structure of pyrimidine with that of benzene revealed pronounced similarities and thus a dominant role of π–π∗ excited states and resonances. Electron energy loss spectra were measured as a preparation for the cross section measurements and vibrational structure was observed for some of the triplet states. A detailed analysis of the electronic excited states of pyrimidine is also presented.