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Inner-Shell Excitation Spectroscopy of Polymer and Monomer Isomers of Dimethyl S. G. Urquhart, A. P. Hitchcock,*, A. P. Smith, H. Ade, and E. G. Rightor
 

Summary: Inner-Shell Excitation Spectroscopy of Polymer and Monomer Isomers of Dimethyl
Phthalate
S. G. Urquhart, A. P. Hitchcock,*, A. P. Smith, H. Ade, and E. G. Rightorž
Department of Chemistry, McMaster UniVersity, Hamilton, Ontario, Canada L8S 4M1, Department of Physics,
North Carolina State UniVersity, Raleigh, North Carolina 27695, and Analytical Sciences, B-1470,
Dow Chemical, Freeport, Texas 77541
ReceiVed: October 31, 1996; In Final Form: January 10, 1997X
The C 1s X-ray absorption spectra (XAS) of poly(diallyl phthalate), poly(diallyl isophthalate), and poly-
(ethylene terephthalate) (PET) have been recorded using transmission detection. The phthalate segments of
these polymers are isomers with different patterns of substitution (ortho, meta, para) of the methyl carboxylate
groups on the phenyl ring. The C 1s and O 1s electron energy loss spectra (EELS) of the corresponding
isomeric monomers, dimethyl phthalate, dimethyl isophthalate, and dimethyl terephthalate, have also been
recorded in the gas phase using inelastic electron scattering under conditions dominated by electric dipole
transitions. Good agreement is found in overall shape and in the energies of the spectral features of the same
isomer in monomeric (EELS) versus polymeric (XAS) form. Ab initio calculations are used to provide a
detailed interpretation of the spectra, in particular the origin of the isomeric variations. The analytical potential
for using inner shell excitation spectroscopy to identify isomeric character and to map spatial distributions of
polymer isomeric substitution is assessed.
1. Introduction
This work extends earlier studies1-3 of the core excitation

  

Source: Ade, Harald W.- Department of Physics, North Carolina State University

 

Collections: Physics