SPECTRAL-ANALYSIS OF 8 POLYMERS IN SIMS BY MO CALCULATION - PREDICTION OF CLEAVAGE OF POLYMERS AND STRUCTURAL FORMULA OF THE POSITIVE-ION FRAGMENT

Spectra of eight polymers [(CH2-CHR)(n) (R=H, OH, F, Cl, OCH3, and CON H2), (CF2-CF2)(n)] and (CH2-CHCN)(n) in time-of-flight (TOF)- and stat ic(S)-secondary ion mass spectrometry (SIMS), respectively, were analy zed by semiempirical and ab initio molecular orbital (MO) calculations . We predicted where the cleavage of the polymers occurs on sputtering , due to two-center bond energies of the model pentamers by a semiempi rical MO calculations using AM1 program; a) the cleavage can occur in any bonds (polyethylene, poly(vinyl methyl ether), polyacrylonitrile), b)the cleavage of the main chain occurs in any bonds, after side chai n groups cleaved first (poly(vinyl chloride, poly(acrylamide)), c) the main chain carbons with the side chain group cleave at any bonds of t he main chain (poly(vinyl fluoride, poly(tetrafluoroethylene), poly(vi nyl alcohol)). We also determined the possible structural formulas of the secondary positive-ion fragments in the range of 0-100 amu by ab i nitio MO calculations using the HONDO7 program.