Two-Dimensional near Infrared Correlation Spectroscopy: Principle and its Applications

1998 ◽  
Vol 6 (1) ◽  
pp. 19-31 ◽  
Author(s):  
Yukihiro Ozaki ◽  
Yan Wang
Keyword(s):  
Correlation Analysis ◽  
Basic Principle ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Correlation Spectroscopy ◽  
Mathematical Treatment ◽  
Two Dimensional ◽  
2D Correlation Spectroscopy

The basic principle and applications of generalised two-dimensional (2D) near infrared (NIR) correlation spectroscopy are reviewed in this paper. A brief history and the basic principle of 2D correlation spectroscopy are described first, and then its importance for NIR spectroscopy is discussed. An outline of the mathematical treatment of generalised 2D correlation spectroscopy is given. Several examples of generalised 2D NIR and 2D NIR-mid IR (MIR) heterospectral correlation analysis are introduced.

Two-Dimensional Vibration Spectroscopy. V: Correlation of Mid- and near Infrared of Hard Red Winter and Spring Wheats

1996 ◽  
Vol 4 (1) ◽  
pp. 139-152 ◽  
Author(s):  
F.E. Barton ◽  
D.S. Himmelsbach ◽  
D.D. Archibald
Keyword(s):  
Raman Spectra ◽  
Spring Wheat ◽  
Near Infrared ◽  
Nir Spectroscopy ◽  
Correlation Spectroscopy ◽  
Analytical Models ◽  
Electromagnetic Spectrum ◽  
Two Dimensional ◽  
Stretching Vibrations ◽  
Agricultural Materials

Two-dimensional correlation spectroscopy across the near infrared (NIR) and mid-infrared (MIR) regions have been used to explain the NIR spectra of hard red winter and spring wheat and provide additional confidence in analytical models developed with empirical data. Recent studies have shown that the major C–H stretching vibrations and some of the aromatic C–H and ring stretching vibrations and the minor vibrations in the “fingerprint” region are correlated also. The technique has been expanded to include Raman spectra. The Raman spectra were enhanced with Maximum Likelihood methods to improve signal-to-noise (S/N) while maintaining resolution. This was necessary to eliminate the effects of fluorescence which degrades S/N. The use of NIR lasers at 1.1 μm generally eliminates fluorescence as a problem, but it is still quite prevalent in agricultural materials. The original study did not show any significant correlations to aromatic functionality. However, the band at 1552 nm correlates to the Raman and not to the MIR. This band has shown up in NIR spectroscopy models for the determination of lignin, but is not readily observed in the MIR. Thus it correlates to a Raman active rather than a MIR active band. The same phenomena are observed for the amide I, II and III bands for wheat. The interesting features from NIR and MIR are that there are correlations that distinguish winter from spring wheat. These, and the Raman spectra of wheat, will be shown. These studies show that multiple regions of the electromagnetic spectrum can be, and in deed need to be, used to interpret adequately the spectral and statistical results we have traditionally obtained in the NIR.

Rheo-Optical Near-Infrared (NIR) Characterization of Hydroxyl-Functionalized Polypropylene (PPOH)-Mesoporous Silica Nanocomposites Using Two-Trace Two-Dimensional (2T2D) Correlation Analysis

2019 ◽  
pp. 000370281986156 ◽  
Author(s):  
Ryota Watanabe ◽  
Hideaki Hagihara ◽  
Hiroaki Sato ◽  
Junji Mizukado ◽  
Hideyuki Shinzawa
Keyword(s):  
Mesoporous Silica ◽  
Near Infrared ◽  
Tensile Deformation ◽  
Nir Spectroscopy ◽  
Amorphous Region ◽  
Amorphous Structure ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Correlation Peak ◽  
Thickness Change

A rheo-optical characterization technique based on the combination of near-infrared (NIR) spectroscopy and mechanical analysis was applied to the nanocomposite consisting of hydroxyl-functionalized polypropylene (PPOH) and mesoporous silica (MPS) to probe the deformation behavior. Substantial levels of spectral changes of NIR spectral features were captured when the polymer samples underwent tensile deformation. Sets of spectra were subjected to projection treatment to remove the effect of baseline fluctuations and thickness change inevitably caused by the tensile deformation of the sample. Then, two-trace two-dimensional (2T2D) correlation spectroscopy was applied to the pretreated spectra to elucidate spectroscopic signature associated with the difference between the initial and deformed samples. An asynchronous correlation peak appears between the bands at 1720 and 1700 nm respectively reflecting the contributions of predominantly amorphous and crystalline component of the PPOH, indicating the predominant variation of amorphous structure followed by that of crystalline structure. In addition, the predominant spectral change related to the amorphous band becomes even more acute by including the MPS with large pores. It is hence likely that the larger pore size of the MPS confines the more amorphous structure, which, in turn, causes simultaneous reorientation of the polymer chains in the amorphous region during the elastic deformation. Consequently, the incorporation of the MPS selectively restricts the deformation of the amorphous structure which eventually provides the obvious increase in the mechanical property of the PPOH polymer.

New Insight into the Mathematical Background of Generalized Two-Dimensional Correlation Spectroscopy and the Influence of Mean Normalization Pretreatment on Two-Dimensional Correlation Spectra

2001 ◽  
Vol 55 (3) ◽  
pp. 343-349 ◽  
Author(s):  
Slobodan Šašić ◽  
Andrzej Muszynski ◽  
Yukihiro Ozaki
Keyword(s):  
Correlation Analysis ◽  
Cross Product ◽  
Correlation Spectroscopy ◽  
Point Of View ◽  
Hilbert Transformation ◽  
Two Dimensional ◽  
Two Component System ◽  
Large Intensity ◽  
Scalar Products ◽  
2D Correlation Spectroscopy

Generalized two-dimensional (2D) correlation spectroscopy is considered from the point of view of linear algebra. It is shown that a synchronous spectrum is the same as the cross-product matrix of the experimental data. An asynchronous spectrum is also treated as the ordered scalar products of the dynamic vectors of the experimental matrix and its Hilbert transformation. This approach connects the theory of generalized 2D correlation spectroscopy with the well-known conceptions of classic correlation analysis. The importance of spectral normalization in the 2D correlation analysis and its influence on the 2D correlation spectra is also investigated. All calculations were done on a synthetic spectral model consisting of two components. The synchronous spectra obtained from the model matrix were compared with those obtained after spectral mean normalization. It was found that the results strongly depend on the pretreatment. We plotted the Hilbert transformation of the meancentered model and found that the normalization leads to the disappearance of the asynchronous spectra in the two-component system. Also, it has been concluded that the influence of normalization is important just for the systems with large intensity variations. All the results presented here are quite general and can be applied irrespective of the nature of the perturbation.

Resolution Enhancement and Band Assignments for the First Overtone of OH Stretching Mode of Butanols by Two-Dimensional Near-Infrared Correlation Spectroscopy. Part I: sec-Butanol

1998 ◽  
Vol 52 (7) ◽  
pp. 994-1000 ◽  
Author(s):  
Mirosław A. Czarnecki ◽  
Hisashi Maeda ◽  
Yukihiro Ozaki ◽  
Masao Suzuki ◽  
Makio Iwahashi
Keyword(s):  
Correlation Analysis ◽  
Near Infrared ◽  
Elevated Temperatures ◽  
Equilibrium Constants ◽  
Thermal Dissociation ◽  
Resolution Enhancement ◽  
Correlation Spectroscopy ◽  
Pure Liquid ◽  
Two Dimensional ◽  
Oh Groups

The first paper in a series devoted to self-association in neat butanols presents the results of two-dimensional (2D) near-infrared (NIR) correlation analysis of temperature-induced spectral variations of sec-butanol. By taking advantage of resolution enhancement in the 2D correlation spectra, it was possible to identify spectral features due to vibrations of the free and associated OH groups in the first-overtone region. On the basis of a few assumptions, band assignments of the various types of OH bonds have been proposed. The monomer band (near 7100 cm−1) can be resolved into three components; two of them are due to a rotational isomerism (7089 and 7116 cm−1), and the third one is attributed to the free terminal OH groups in linear polymers (7055 cm−1). The presence of the 7055 cm−1 band implies that the intensity of the monomer peak cannot be used as a measure of the concentration of the monomer species (except in very diluted solutions). Thus, previous estimations of equilibrium constants and thermodynamic parameters associated with hydrogen-bond dissociation have been subject to unacceptable error. At higher temperatures, a new band near 6550 cm−1 becomes visible. This band originates from bended OHO bond, mostly in the cyclic polymers. In order to obtain more detailed information on the complex mechanism of the thermal dissociation of hydrogen-bonded sec-butanol in the pure liquid phase, the entire experimental temperature range was divided into narrower ranges, and then 2D correlation analysis was performed for smaller data sets. It has been shown that the variations of population of the polymeric species and the cyclic dimers are faster than the corresponding changes for the monomers. At elevated temperatures an appreciable dissociation of the cyclic species takes place.

Identification of Overlapped Near-Infrared Bands of Glucose Anomers Using Two-Dimensional Near-Infrared and Middle-Infrared Correlation Spectroscopy

2002 ◽  
Vol 56 (7) ◽  
pp. 897-901 ◽  
Author(s):  
Aminiel Awichi ◽  
Eric M. Tee ◽  
Giri Srikanthan ◽  
Wei Zhao
Keyword(s):  
Mixed Mode ◽  
Near Infrared ◽  
Spectroscopic Method ◽  
Nir Spectroscopy ◽  
Correlation Spectroscopy ◽  
Two Dimensional ◽  
Combination Band ◽  
Spectral Changes ◽  
Glucose Anomers ◽  
Middle Infrared

Near-infrared (NIR) spectroscopy is a useful tool in determining glucose in biological matrices. Because α-anomers and β-anomers of glucose are in equilibrium in the solution, the observed NIR bands may come from the overlapping of vibrational modes of the anomers. We have conducted NIR and mid-infrared (MIR) absorption spectra measurements to determine the nature of the observed NIR features by using two-dimensional (2D) NIR and MIR correlation spectroscopy. The 2D NIR correlation spectra and 2D synchronous NIR and MIR correlation heterospectra are constructed based on the spectral changes of individual anomers upon mutarotation. We have identified a new NIR feature at 4350 cm−1 for the α-anomers and two new NIR features at 4200 and 4250 for the β-anomers. The 4350-cm−1 band of the α-anomers could be assigned to the combination band of C–H stretch at 2945 cm−1 and a mixed mode of C–H bending and O–H bending at 1415 cm−1. The 4200/4250-cm−1 bands of the β-anomers might be tentatively assigned to the combination band of C–H stretching at 2870 cm−1 and a mixed mode of C–H bending and O–H bending at 1315/1370 cm−1. This finding provides the spectral information needed for implementation of a highly selective coherent two-dimensional vibrational spectroscopic method, the DOVE-Raman four wave mixing for selective identification of glucose anomers from aqueous solutions.

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