An investigation into allegations of double scattering in the carbon K-shell electron energy loss spectrum of acetylene

In several recent publications (R. G. Cavell and D. A. Allison, J. Chem. Phys., 69 (1978) 159; A. Barth et al., Chem. Phys., 46 (1980) 149) it has been suggested that the feature at 295.6 eV energy loss in the carbon K-shell spectrum of C2H2 may arise from double scattering (i.e., collisions of one electron with two acetylene molecules). The pressure-dependence of the carbon K-shell excitation spectrum of C2H2 has been examined by inelastic scattering of 2.5-keV electrons to investigate this possibility. The intensity of all features, including that at 295.6 eV, was observed to vary linearly with pressure, indicating that the spectral features arise only from single collisions.