Intracluster Ion/Molecule Reactions within 1, 1-Difluoroethylene Homocluster

Abstract

The intracluster ion/molecule reactions within 1,1-difluoroethene homocluster have been studied by electron-impact quadrupole mass spectrometry. When CH(2)CR(2) seeded in helium is expanded and ionized by electron impact, two different types of ion/molecule association (polymerization) reaction products, i.e., (CH2CF2)(n)(+) (n greater than or equal to 1) and (CF2CH2)(q)X(+) (X=fragment species, gin), are formed. The higher association products, (CH2CF2)(n)(+) (n=3, 4), have shown stronger intensities over the lower association product, (CH2CF2)(2)(+), in the low electron impact energy region (<39 eV). These stronger intensities are interpreted in terms of the stabilization of these ions due to the ring formations over the dimer ion in this energy region. The evidence of ring formation mechanism is on the basis of the intensity distribution of fragments at various electron impact energy. In another typical branched-chain growth reaction of these compounds, the F-shift reaction path is found to be more favorable energetically than the H-shift via the fragment patterns of clusters and semi-empirical calculation.