星野 正光

A new apparatus combining the crossed-beam method and the threshold-ionization technique has been developed to measure absolute cross sections for electron impact dissociation of CH4 into neutral fragments. A Continuum Multiple Scattering code has also been developed and used to study the neutral radical decay pathways in these molecules. Details of the two methods and results obtained so far are presented in this paper.

This paper reports on the first measurements of the electron impact electronic excitation cross sections for hexafluoropropene (C3F6) measured at the two experimental conditions of 20 eV and 10 degrees, and 100 eV and 5 degrees, while sweeping the energy loss over the range 2-14 eV. Similarity between these two spectra shows the insignificance of optically forbidden transitions in these molecules. Three broad features have been observed at about 7, 7.5, and 8.2eV and attributed to the C = C pi -> C-F sigma*; C = C pi -> C = C sigma* (both dissociative); and 8.2 eV, due to C = C pi -> C = C pi* excitations. The EELS for impact energy 100 eV and angle 5 degrees rise rapidly above I I eV and shows a broad resonance structure centered around 12.7 eV. Similarities in the repulsive energy loss features have been observed in the comparative study of the C3F6 EELS for 100eV, 5 degrees with the similar one for C2F4 and attributed to the common electronic transitions into C=C antibonding orbitals, albeit with peak position differences below 10 eV.