scholarly journals Vibration-rotation spectra of hydrogen halides in rare-gas liquids: Q-branch absorption

2004 ◽  
Vol 76 (1) ◽  
pp. 241-246 ◽  
Author(s):  
A. Medina ◽  
J. M. M. Roco ◽  
A. C. Hernández ◽  
S. Velasco
Keyword(s):  
Near Infrared ◽  
Rare Gas ◽  
Physical Origin ◽  
Hydrogen Halides ◽  
Induced Dipole ◽  
Near Infrared Spectra ◽  
Physical Effects ◽  
Intense Absorption ◽  
Vibration Rotation ◽  
Dynamics Simulations

Near-infrared spectra of HCl highly diluted in liquid Ar show intense absorption in the P-R interbranch region, so-called Q-branch absorption. In spite of its relevance for the shape of the bands, its physical origin has been elusive to date. We employ molecular dynamics simulations to study the influence of some physical effects that could contribute to Q-branch absorption. We check that multipole-induced dipole induction mechanisms are not quantitatively relevant in this spectral region. We show that the particular characteristics of accurate HCl-Ar anisotropic potentials and the peculiar hindered rotational motion they provoke on the diatomic probe are essential to understand Q-branch absorption.

Vibration-rotation spectra of HCl in rare-gas liquid mixtures: Molecular dynamics simulations of Q-branch absorption

2002 ◽  
Vol 116 (12) ◽  
pp. 5058 ◽  
Author(s):  
A. Medina ◽  
J. M. M. Roco ◽  
A. Calvo Hernández ◽  
S. Velasco ◽  
M. O. Bulanin ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Liquid Mixtures ◽  
Rare Gas ◽  
Vibration Rotation ◽  
Dynamics Simulations

Effect of Resolution on the Wavelength Determination of a Putative Standard to Be Used for near Infrared Diffuse Reflection Spectra Measured on Grating Spectrometers

2003 ◽  
Vol 11 (4) ◽  
pp. 229-240 ◽  
Author(s):  
Husheng Yang ◽  
Tomas Isaksson ◽  
Richard S. Jackson ◽  
Peter R. Griffiths
Keyword(s):  
Near Infrared ◽  
Diffuse Reflection ◽  
Powdered Sample ◽  
Near Infrared Spectra ◽  
Wavelength Standard ◽  
The Us ◽  
Wavelength Resolution ◽  
Grating Monochromator ◽  
Vibration Rotation ◽  
Better Than

Diffuse reflection (DR) Fourier transform near infrared spectra of a powdered mixture of Er2O3, Dy2O3, Ho2O3 and talc were measured at a constant resolution of at least 2 cm−1 on four different combinations of spectrometers and sampling accessories. The wavenumber scale of each of these spectra was corrected with lines in the vibration–rotation spectrum of water vapour so that the accuracy was better than 0.02 cm−1. DR spectra of the powdered sample were then calculated at constant-wavelength resolution to simulate spectra that would have been measured on a grating monochromator. The precision and accuracy of the bands in the spectrum of this sample were then estimated. It is believed that the accuracy of the reported positions of the bands in the spectrum of this putative wavelength standard is about ten times better than the corresponding values in the DR spectrum of a mixture of Er2O3, Dy2O3 and Ho2O3 that had previously been reported by the US National Institute of Standards and Technology.

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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