The near-infrared spectra of some simple aldehydes

1970 ◽  
Vol 48 (23) ◽  
pp. 3694-3703 ◽  
Author(s):  
G. Lucazeau ◽  
C. Sandorfy
Keyword(s):  
Liquid Nitrogen ◽  
Infrared Spectra ◽  
Solvent Effects ◽  
Near Infrared ◽  
Fermi Resonance ◽  
Near Infrared Spectra ◽  
Anharmonicity Constants

The near-infrared spectra of CH3CHO, CD3CHO, CH3CDO, CF3CHO, CHCl2CHO, and CCl3CHO were measured from 4000 to 9000 cm−1 in solution at room and liquid nitrogen temperatures. Assignments are made and cases of Fermi resonance are examined. A few potential and anharmonicity constants are obtained. Solvent effects affecting fundamentals and overtones are discussed.

Near-infrared spectra of Ba(NO2)2•X2O (X = H,D) at 10 K. A local-mode approach

1997 ◽  
Vol 75 (8) ◽  
pp. 1099-1105 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Fermi Resonance ◽  
Strong Hydrogen Bond ◽  
Local Mode ◽  
Morse Oscillator ◽  
Near Infrared Spectra ◽  
Bifurcated Hydrogen Bond

The fundamental and overtone vibrational spectra of Ba(NO2)2•X2O (X=H,D) have been interpreted using the local mode model. The calculated parameters are consistent with the structure, which has one strong hydrogen bond and one weak bifurcated hydrogen bond. Evidence for Fermi resonance between stretch and bend features having similar energies is discussed. Evidence for the breakdown of the simple Morse oscillator model, which was quite successful for [Formula: see text] hydrogen bonds, is also presented. Keywords: overtone, spectra, near-infrared, hydrates, local-mode model.

Polarized overtone-combination bands in the near-infrared spectra of K2SnCl4•H2O and KSnCl3•H2O at cryogenic temperatures

1986 ◽  
Vol 64 (5) ◽  
pp. 1012-1019 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Water Molecule ◽  
Normal Mode ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Water Molecules ◽  
Site Symmetry ◽  
Cryogenic Temperatures ◽  
Near Infrared Spectra ◽  
Combination Bands ◽  
Anharmonicity Constants

The near-infrared (nir) spectra of K2SnCl4•H2O and KSnCl3•H2O contain many highly polarized absorptions, due largely, if not completely, to combinations of vibrations of the water molecules in the crystals. The polarization of the absorptions can be related to the site symmetry of the water molecule. In K2SnCl4•H2O combination bands based on rocking, wagging, and twisting librations are seen, from which it is possible to definitively identify the rocking libration. The librations are much less in evidence in the spectra of KSnCl3•H2O. Sets of normal mode anharmonicity constants have been calculated from the energies of the absorptions.

Rapid Determining Contents of the Rhubarb Anthraquinones Compounds by Support Vector Machines Modeling based on Near Infrared Spectra

2020 ◽  
Vol 16 ◽  
Author(s):  
Linqi Liu ◽  
JInhua Luo ◽  
Chenxi Zhao ◽  
Bingxue Zhang ◽  
Wei Fan ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Mean Squared Error ◽  
Rapid Determination ◽  
Partial Least Square ◽  
Least Square ◽  
Support Vector ◽  
Near Infrared Spectra ◽  
Aloe Emodin ◽  
Relative Differences

BACKGROUND: Measuring medicinal compounds to evaluate their quality and efficacy has been recognized as a useful approach in treatment. Rhubarb anthraquinones compounds (mainly including aloe-emodin, rhein, emodin, chrysophanol and physcion) are its main effective components as purgating drug. In the current Chinese Pharmacopoeia, the total anthraquinones content is designated as its quantitative quality and control index while the content of each compound has not been specified. METHODS: On the basis of forty rhubarb samples, the correlation models between the near infrared spectra and UPLC analysis data were constructed using support vector machine (SVM) and partial least square (PLS) methods according to Kennard and Stone algorithm for dividing the calibration/prediction datasets. Good models mean they have high correlation coefficients (R2) and low root mean squared error of prediction (RMSEP) values. RESULTS: The models constructed by SVM have much better performance than those by PLS methods. The SVM models have high R2 of 0.8951, 0.9738, 0.9849, 0.9779, 0.9411 and 0.9862 that correspond to aloe-emodin, rhein, emodin, chrysophanol, physcion and total anthraquinones contents, respectively. The corresponding RMSEPs are 0.3592, 0.4182, 0.4508, 0.7121, 0.8365 and 1.7910, respectively. 75% of the predicted results have relative differences being lower than 10%. As for rhein and total anthraquinones, all of the predicted results have relative differences being lower than 10%. CONCLUSION: The nonlinear models constructed by SVM showed good performances with predicted values close to the experimental values. This can perform the rapid determination of the main medicinal ingredients in rhubarb medicinal materials.

Discrimination of transgenic tomatoes based on visible/near-infrared spectra

2007 ◽  
Vol 584 (2) ◽  
pp. 379-384 ◽  
Author(s):  
Lijuan Xie ◽  
Yibin Ying ◽  
Tiejin Ying ◽  
Haiyan Yu ◽  
Xiaping Fu
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Near Infrared Spectra ◽  
Transgenic Tomatoes

Mid and near Infrared Study of Carbohydrates by Canonical Correlation Analysis

1993 ◽  
Vol 1 (2) ◽  
pp. 99-108 ◽  
Author(s):  
P. Robert ◽  
M.F. Devaux ◽  
A. Qannari ◽  
M. Safar
Keyword(s):  
Correlation Analysis ◽  
Infrared Spectra ◽  
Canonical Correlation ◽  
Near Infrared ◽  
Sugar Content ◽  
Infrared Region ◽  
Total Sugar ◽  
Mid Infrared ◽  
Total Sugar Content ◽  
Near Infrared Spectra

Multivariate data treatments were applied to mid and near infrared spectra of glucose, fructose and sucrose solutions in order to specify near infrared frequencies that characterise each carbohydrate. As a first step, the mid and near infrared regions were separately studied by performing Principal Component Analyses. While glucose, fructose and sucrose could be clearly identified on the similarity maps derived from the mid infrared spectra, only the total sugar content of the solutions was observed when using the near infrared region. Characteristic wavelengths of the total sugar content were found at 2118, 2270 and 2324 nm. In a second step, the mid and near infrared regions were jointly studied by a Canonical Correlation Analysis. As the assignments of frequencies are generally well known in the mid infrared region, it should be useful to study the relationships between the two infrared regions. Thus, the canonical patterns obtained from the near infrared spectra revealed wavelengths that characterised each carbohydrate. The OH and CH combination bands were observed at: 2088 and 2332 nm for glucose, 2134 and 2252 nm for fructose, 2058 and 2278 nm for sucrose. Although a precise assignment of the near infrared bands to chemical groups within the molecules was not possible, the present work showed that near infrared spectra of carbohydrates presented specific features.

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