Multiple Peak Reference Method for Polarized Fourier Transform Infrared–Attenuated Total Reflection Spectroscopy to Determine the Three-Dimensional Orientation of a Uniaxially Drawn Poly(trimethylene 2,6-naphthalate) Film

Author： Liang Yongri Choi Ki Woon Lee Han Sup

Publisher： Society for Applied Spectroscopy

ISSN： 0003-7028

Source： Applied Spectroscopy, Vol.62, Iss.12, 2008-12, pp. : 1314-1321

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Abstract

The polarized Fourier transform infrared–attenuated total reflection (FT-IR-ATR) technique is a very useful infrared spectroscopic method for characterizing the three-dimensional orientation of thick samples, to which the conventional transmission FT-IR method cannot easily be applied. To quantitatively analyze polarized FT-IR-ATR spectra, the dependence of the optical contact between the sample and the ATR crystal during the clamping and reclamping processes must be controlled. In this work, a new multiple peak reference (MPR) method is proposed and used to carry out a three-dimensional analysis of a poly(trimethylene 2,6-naphthalate) (PTN) polymer sample. The conventional single peak reference (SPR) analysis technique cannot be applied to such a sample due to the lack of an established reference peak. A new artificial reference band was generated by the MPR method using two different infrared bands, at 1602 cm⁻¹ and 917 cm⁻¹, in identical spectra with a combination constant of 0.95. The new artificial reference band was successfully used to calculate the three-dimensional orientation of various infrared bands of a uniaxially drawn PTN film, which has not previously been studied by three-dimensional orientation analyses using the polarized FT-IR-ATR method.