Concerning the spectral resolution enhancement of dynamic 2D-IR

A dynamic two-dimensional infrared (2D-IR) spectroscopic study of a hydrogen bonded polymer blend, poly(vinyl phenol) (PVPh)/poly(methyl acrylate) (PMA), in the CO stretching range was conducted to investigate one of the major features of this technique, i.e., spectral resolution enhancement. It was found that peak positions in the in-phase dynamic spectrum are different from the ones in the traditional Fourier transform infrared spectrometry (FT-IR) spectrum, which is a result of the subtraction procedure to obtain the former. In addition, the intensities of quadrature spectra are extremely low, which are easily affected by noise or interference, etc. Dynamic 2D-IR plots constructed from such dynamic spectra may produce new features that are actually artifacts. Thus, new features revealed by dynamic 2D-IR spectroscopy have to be interpreted with extreme care. To improve the quality of dynamic FT-IR and thereby the dynamic 2D-IR spectra, new strategies must be sought.