Modern Polymer Spect..

1'
1656
1661
1669
1679
I I I I I I I I I 1 1788
BE 1650 1608
Wavenumber, u,
Figure 1-26. An asynchronous ZD IR spectrum in the amide I vibration region of a film made of
solubilized human hair keratin 1441.
1.6 Further Extension of 2D Correlation Technique
The basic concept of 2D IR spectroscopy based on the correlation analysis of
perturbation-induced time-dependent fluctuations of IR intensities could be readily
extended to other areas of polymers spectroscopy. The 2D correlation analysis has
been successfully applied to the time-dependent variations of small angle X-ray
scattering intensity measurement [4]. In this study, a small amplitude dynamic
strain is applied a sheet of microphase-separated styrene-butadiene-styrene triblock
copolymer sample. Intensity variation of scattered X-ray beam due to the
strain-induced changes in the interdomain Bragg distances coupled with the reorientation
of microdomain structures is analyzed by using the 2D correlation map.
Similarly, the formal approach of 2D correlation analysis to time-dependent spectral
intensity fluctuations has been extended to UV, Raman [63), and near-IR
spectroscopy (641. There seems no intrinsic limitation to the application of this
versatile technique in polymer spectroscopy.
The introduction of the generalized 2D correlation method [8] has made it possible
to further extend the utility of 2D correlation analysis beyond the study of
simple sinusoidally varying dynamic spectral signals as originally described in Eqs.
(1-2) and (1-3). By utilizing the time-domain Fourier transform of spectral intensity
variations, a formal definition of 2D correlation spectra resembling Eq. (1-9) can be