The identification and origin of N-H group overtone and combination bands in the near infrared spectra of 2-thiopyrrole-l,2-dicarboximides

1986 ◽  
Vol 96 (1-2) ◽  
pp. 73-83
Author(s):  
S. Ram ◽  
O. P. Lamba ◽  
J. S. Yadav
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Near Infrared Spectra ◽  
Combination Bands

HYDROGEN BONDING IN THE AMINE HYDROHALIDES: III. NEAR-INFRARED SPECTRA OF ALIPHATIC AMINE HYDROHALIDES

1960 ◽  
Vol 38 (10) ◽  
pp. 1901-1910 ◽  
Author(s):  
P. Sauvageau ◽  
C. Sandorfy
Keyword(s):  
Hydrogen Bonding ◽  
Secondary Amine ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Potential Surface ◽  
Aliphatic Amine ◽  
Bending Vibrations ◽  
Near Infrared Spectra ◽  
Combination Bands

The first overtones of the [Formula: see text] stretching fundamentals are very weak and difficult to locate. Binary combinations between [Formula: see text] stretching and [Formula: see text] bending vibrations and also [Formula: see text] stretching–bending combinations fall into the 4600–4400 cm−1 area for primary and secondary amine hydrohalides and are much stronger. The intensity of these combination bands is not due to the anharnionicity of the potential surface but to the electrical anharmonicity of bending vibrations.

Measurement of the Near-Infrared Spectra of H2O-SiOH-Bearing Siliceous Materials at High Pressures

1979 ◽  
Vol 33 (5) ◽  
pp. 495-499 ◽  
Author(s):  
Klaus Langer ◽  
Werner A. P. Luck ◽  
Otto Schrems
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
High Pressures ◽  
Band System ◽  
High Energy ◽  
Single Beam ◽  
Near Infrared Spectra ◽  
Diamond Anvil ◽  
Combination Bands ◽  
Energy Components

Techniques for measuring OH-combination bands of water and other OH-group bearing solid or liquid materials in the near-infrared (6000 to 4000 cm−1) at high pressures by means of a modified diamond anvil cell, adapted to a single beam micro-spectrometer, have been developed and applied to opals, i.e., minerals in the system SiO2-H2O containing relatively high amounts of water and SiOH. Liquid embedding, using the gasket technique and poly-fluoro-carbon oils as embedding liquids, which provide a hydrostatic pressure environment at least up to 50 kbar, is applied for solid materials. The high pressure near-infrared spectra of gel-like, spherulitic opal-AG show a strong relative decrease of the high energy components of the complex (v1 + v2)H2O-band system at around 5200 cm−1 in favor of the low energy components of this band system. This is tentatively interpreted as due to an increase of fully hydrogen bonded water at the expense of water in which only one OH-group is H-bonded. The corresponding effect in opal-AN with a glass-like continuous SiO4/2-tetrahedral network is much smaller.

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.

HYDRATED SULFATES ON MARS: CHARACTERIZING VISIBLE TO NEAR-INFRARED SPECTRA AND IMPLICATIONS FOR ROVER-BASED MULTISPECTRAL IMAGERS

2016 ◽  
Author(s):  
Darian T. Dixon ◽  
◽  
Melissa S. Rice ◽  
Edward A. Cloutis
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Near Infrared Spectra

Assessing black tea quality based on visible–near infrared spectra and kernel-based methods

2021 ◽  
Vol 98 ◽  
pp. 103810
Author(s):  
Guangxin Ren ◽  
Ying Liu ◽  
Jingming Ning ◽  
Zhengzhu Zhang
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Black Tea ◽  
Near Infrared Spectra ◽  
Tea Quality

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

Effect of wavelet denoising techniques on the determination of navel orange sugar content with near-infrared spectra

2006 ◽  
Author(s):  
Lijuan Xie ◽  
Haibo Huang ◽  
Yibin Ying ◽  
Huishan Lu ◽  
Xiaping Fu
Keyword(s):  
Infrared Spectra ◽  
Near Infrared ◽  
Sugar Content ◽  
Wavelet Denoising ◽  
Navel Orange ◽  
Near Infrared Spectra
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