We report threshold electron energy-loss spectra for the fluorohalomethanes CF 3 X ͑X =Cl,Br͒. Measurements were made at incident electron energies of 30 and 100 eV in energy-loss range of 4 -14 eV, and at scattering angles of 4°and 15°. Several new electronic transitions are observed which are ascribable to excitation of low-lying states as well as are intrinsically overlapped in the molecules themselves. Assignments of these electronic transitions are suggested. These assignments are based on

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... present spectroscopic and cross-section measurements, high-energy scattering spectra, and ab initio molecular orbital calculations. The calculated potential curves along the C -X bond show repulsive nature, suggesting that these transitions may lead to dissociation of the C -X bond. The present results are also compared with the previous ones for CF 3 H, CF 4 , and CF 3 I.