Two-dimensional infrared (2D IR) correlation spectroscopy study of self-assembly of oleic acid (OA) in conjunction with partial attenuation of dominant factor by eigenvalue manipulating transformation (EMT)

Highly selective two-dimensional (2D) correlation analysis, achieved by attenuating a major principal component in spectral data with eigenvector manipulating transformation (EMT) technique, was demonstrated. A spontaneous evaporation process of a binary mixture solution of oleic acid (OA) and carbon tetrachloride (CCl4) was monitored by attenuated total reflection infrared (ATR-IR) spectroscopy. Fine details of the dynamic behavior of OA molecules undergoing self-assembly into smectic liquid crystals were analyzed by 2D correlation spectroscopy scheme in conjunction with EMT technique. Correlation feature derived from the original spectral data is dominated with the contribution from the major dimer components of OA. On the other hand, 2D correlation spectra generated form the reconstructed data by attenuating the first principal component (PC1) showed selective enhancement of the correlational feature associated with the minor monomer component, which makes it possible to identify distinct populations, each having different dynamic behavior during the self-assembly.