Two-Dimensional Correlation Spectroscopy: The Power of Power Spectra

Abstract

Power spectra are a powerful tool provided by two-dimensional correlation analysis. However, this tool is seldom used in practice. This work shows selected examples of using of the power spectra for the study of various kinds of samples with the aim to promote more common use of this tool. By examination of the power spectrum of specific sample, one can estimate the sensitivity of different molecular fragments on a given perturbation. Determination of the power spectra for smaller data subsets provides information on the dynamics of perturbation-induced spectral changes. If the experimental spectra of different samples in the same perturbation window are recorded, the comparison of the power spectra yields information on differences in the sensitivity of various samples on common perturbation. This possibility is particularly useful for studies of the spectra-structure correlations, interactions, and molecular dynamics. A comparison of the power spectra obtained by using different reference spectra provides information on the nature of spectral changes at different wavenumbers.

Identification method for unsteady friction of tool flank for high efficiency milling cutter

“…20,21 Moreover, utilizing power spectra and cross-correlation functions of the instantaneous friction behavior on the tooth’s flank face enables the quantitative estimation of the chaotic characteristics of the instantaneous friction behavior on the milling cutter’s flank face during the entire cutting period, along with its sensitivity to milling vibrations. 4,22,23 To address this, this paper focuses on the impact of milling vibrations and tooth errors on the milling cutter and its tooth’s instantaneous cutting posture. An instantaneous friction variable calculation model for the tooth’s flank face is established.…”

Intermolecular Interactions in the Polymer Blends Under High-Pressure CO2 Studied Using Two-Dimensional Correlation Analysis and Two-Dimensional Disrelation Mapping

“…7,9,12 It can also be used to study intermolecular interactions. [13][14][15] As an extension of conventional 2D correlation analysis, disrelation mapping, proposed by Shinzawa et al in 2017, is a technique to highlight the specific areas where disrelated variation occurs between Wavenumber 1 (n 1 ) and Wavenumber 2 (n 2 ). To be more specific, a convolution filter, which can be viewed as a spatial filter based on the 2D correlation function, was designed to identify the places where an out-of-phase change in the absorbance of two different spectral bands occurs.…”