Computational simulations and a practical application of moving-window two-dimensional correlation spectroscopy

Characteristic features of a moving-window two-dimensional (MW2D) correlation spectrum are investigated by using a set of simulated data, and certain advantages of the MW2D correlation analysis compared with a conventional generalized 2D correlation spectroscopy are demonstrated. Complicated spectral intensity changes along the perturbation direction, such as sigmoidal variations, can be easily discriminated, and their characteristic perturbation points are precisely found by the MW2D correlation analysis. Under a simplifying assumption, a MW2D correlation spectrum is viewed somewhat similar to the squared derivative of the spectrum along the perturbation axis. Computational simulation results indicate that the MW2D correlation analysis is more robust than the squared derivative analysis, i.e., the MW2D correlation analysis is less susceptible to the spectral noise. The insights obtained from the simulated results are applied to the analysis of temperature-dependent IR spectra of poly(methyl methacrylate) (PMMA). Glass transition temperature of PMMA can be clearly found by the MW2D correlation analysis.