In order to characterize surface molecular orientation in three dimensions and to obtain other structural information such as the degree of crystallinity and the different conformer contents at the surface, a new ATR (attenuated total reflection) attachment was designed for FT IR ATR dichroism studies. This holder allows a wide range of well-defined incidence angles to the crystal, thereby allowing depth profiling, and when combined with an improved optical arrangement, provides increased sensitivity. In order to demonstrate the applicability of this new attachment, films of uniaxially drawn polypropylene (PP), polyethylene terephthalate) (PET), and biaxially drawn PP were characterized in this study, along with undrawn polypropylene for comparison. For uniaxially drawn polymers, the three-dimensional absorbances show that even though the major anisotropy exists between the draw direction (x) and the transverse direction (y) or between x and the thickness direction (z), the absorbance along the y or z direction is not identical in some bands, suggesting a certain extent of deviation from transverse symmetry. The surface degree of crystallinity in PP, averaging a depth of about 3 µ , has been estimated from the three absorbance values, after correction for the orientation effect, to be 0.62, 0.72, and 0.45 for uniaxially, biaxially, or undrawn films, respectively. These values agree favorably with their bulk crystallinity values obtained by other techniques. On the surface of uniaxially drawn PET, the amount of trans conformer in the ethylene glycol unit of PET is estimated to be at least 49%, and the surface degree of crystallinity to be 0.27. In equally biaxially drawn PP, surface orientation shows a slight imbalance in the two draw directions, while the orientation in the thickness direction is much smaller, as expected. The amorphous orientation functions calculated from our results always show smaller values than the crystalline orientation functions in both PP and PET regardless of whether they were uniaxially or biaxially drawn. Depth-profiling studies within the depth range 1-15 µ enable detection of the gradient in orientation as well as the changing degree of crystallinity near the surface. This technique therefore represents a new, rapid, nondestructive way to characterize surface structure and orientation in polymer fdms as a function of surface depth.

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The isotropic magnetic susceptibility, χiso, for F2 has been measured experimentally for the first time and found to be (−9.627 ± 0.062) × 10-6 (cgs). The value was measured on a paramagnetic gas analyzer (PGA) configured to be compatible with the aggressive F2. The PGA was shown to respond linearly with χiso and was calibrated using the response from several pure gases and their literature χiso values. The major source of error in the analysis is the inaccuracy of the literature χiso values. The experimental result for F2 was compared to ab initio calculations using both Hartree−Fock (HF) theory and gradient-corrected density functional theory (DFT) theory with a variety of basis sets. DFT calculations were found to converge to a value much closer to the experimental value compared to HF calculations, underlining the importance of the many-electron correlation effect in F2.