FLUORINATION EFFECTS IN ELECTRON SCATTERINGS FROM CH4, CH3F1, CH2F2, CH1F3, AND CF4

A conspicuous fluorination effect, prominent structures in elastic dif ferential cross sections below 100 eV, in electron-methane and fluorom ethanes (CH4, CH3F1, CH2F2, CH1F3, and CF4) collisions has been found in a systematic manner. The effect becomes more prominent when the num ber 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 t o interferences of a scattered electron from different scattering cent ers. Therefore, we have examined a possibility of utilizing the undula tion as a means for molecular structure analysis. For these observed f eatures, a simple, intuitively correct interpretation based on the und erlying molecular structure and scattering physics has been given. [S1 050-2947(97)50811-0].