Resonance transitions in electron-impact ionization of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>CF</mml:mi> <mml:mn>4</mml:mn> </mml:msub> </mml:math> studied by angle-resolved <mml:math xmlns:mml="http://www.w3.or

This paper investigates shape resonances in the electron-impact ionization of ${\mathrm{CF}}_{4}$. To this end, scattered-electron--fragment-ion coincidence experiments have been conducted for the molecule, employing an incident electron energy of 1.4 keV and a range of scattering angles from $2.{2}^{\ensuremath{\circ}}$ to $6.{8}^{\ensuremath{\circ}}$. The ionization spectra of the $C\phantom{\rule{0.16em}{0ex}}^{2}T_{2}$ ${(3{t}_{2})}^{\ensuremath{-}1}$ and $D\phantom{\rule{0.16em}{0ex}}^{2}A_{1}$ ${(4{a}_{1})}^{\ensuremath{-}1}$ channels have been constructed from the scattered-electron--${\mathrm{CF}}_{2}{}^{+}$-ion coincidence signals obtained. A resonance band at electron energy loss of $E\ensuremath{\sim}24\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$ in the $C\phantom{\rule{0.16em}{0ex}}^{2}T_{2}$ ionization channel is found to exhibit momentum-transfer dependence characteristic of a dipole-allowed transition and is attributed to the $3{t}_{2}\ensuremath{\rightarrow}\ensuremath{\varepsilon}{t}_{2}$ excitation. The spectra of the ionization to the $D\phantom{\rule{0.16em}{0ex}}^{2}A_{1}$ state manifest a broad peak centered at $E\ensuremath{\sim}27\phantom{\rule{0.16em}{0ex}}\mathrm{eV}$, and its momentum-transfer dependence indicates that this newly identified band arises from a transition to a dipole-forbidden resonance level. The present study demonstrates that angle-resolved $(e,$ $e+\mathrm{ion})$ spectroscopy is a powerful means to investigate shape resonances in the nondipole ionization of molecules, and the outcomes provide a foundation for elucidating the impact of resonance transitions on molecular processes induced by electron impact.