Fluorination effects in electron scatterings from CH₄, CH₃F₁, CH₂F₂, CH₁F₃, and CF₄

A conspicuous fluorination effect, prominent structures in elastic differential cross sections below 100 eV, in electron-methane and fluoromethanes (CH₄, CH₃F₁, CH₂F₂, CH₁F₃, and CF₄) collisions has been found in a systematic manner. The effect becomes more prominent when the number of fluorine atoms increases. Further, a systematic undulation due to F atoms at small-angle scatterings has also been observed, and the case has been studied in detail, in which we have found it to be due to interferences of a scattered electron from different scattering centers. Therefore, we have examined a possibility of utilizing the undulation as a means for molecular structure analysis. For these observed features, a simple, intuitively correct interpretation based on the underlying molecular structure and scattering physics has been given.