Single crystal polarized spectra in the near-infrared region: a local-mode analysis of the spectra of CsMnCl3•2X2O (X = H, D)

1994 ◽  
Vol 72 (5) ◽  
pp. 1211-1217 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Hydrogen Bond ◽  
Near Infrared ◽  
Infrared Region ◽  
Chloride Ions ◽  
Mode Analysis ◽  
Local Mode ◽  
Local Modes ◽  
Near Infrared Spectra ◽  
Parameter Values ◽  
Local Mode Analysis

Polarized near-infrared spectra of single crystals of CsMnCl3•2X2O (X = H, D) were recorded at 10 K. Those bands which could be assigned to O—H or O—D stretch overtones were analyzed using local-mode theory specifically adapted for systems having less than C2v symmetry. Both O—H oscillators form nearly linear hydrogen bonds to neighboring chloride ions at different distances. As a result, the local-mode harmonic frequency and anharmonicity parameters show characteristic shifts from their gas-phase values. The parameter values cover an unusually narrow range in this crystal, considering the spread in hydrogen-bond distances. Assignment of stretch overtone bands to specific oscillators in the crystal was made by using the polarization behavior expected of local modes in the oriented gas model. Several of the overtone bands show combinations with lattice modes or low-energy hydrogen-bond modes in unusual detail.

Single-crystal polarized spectra in the near-infrared region: a local-mode analysis of the spectra of M2MnCl4•2X2O (M = Cs, Rb; X = H, D)

1996 ◽  
Vol 74 (2) ◽  
pp. 246-253 ◽  
Author(s):  
Ian M. Walker ◽  
Paul J. McCarthy
Keyword(s):  
Hydrogen Bond ◽  
Single Crystal ◽  
Near Infrared ◽  
Infrared Region ◽  
Fermi Resonance ◽  
Mode Analysis ◽  
Local Mode ◽  
Bending Mode ◽  
Near Infrared Region ◽  
Local Mode Analysis

The polarized crystal spectra of M2MnCl4•2X2O (M = Cs, Rb; X = H, D) have been measured at 10 K in the near-infrared region. The data have been analyzed using a local-mode model that includes the bending mode. The resulting parameters are related to hydrogen bonding in the crystals. The spectra of partially deuterated species show a large number of bands due to HOD vibrations. The parameters from these spectra are compared to those from the H2O and D2O spectra. Arguments as to the importance of Fermi resonance in these spectra are presented. Key words: near-infrared, single crystal, hydrogen bond, Fermi resonance.

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.

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.

High resolution spectroscopic study of H2 Se (40+,0) A1 and (40-,0) B2 stretching states: normal mode and local mode analysis

1997 ◽  
Vol 92 (6) ◽  
pp. 1073-1082 ◽  
Author(s):  
By ZE-YI ZHOU ◽  
XIAO-GANG WANG ◽  
ZHONG-PING ZHOU ◽  
OLEG N. ULENIKOV ◽  
GALINA A. ONOPENKO ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectroscopic Study ◽  
Normal Mode ◽  
Mode Analysis ◽  
Local Mode ◽  
Local Mode Analysis

Quantum mechanical simulations of near-infrared spectra of biomolecules – Long-chain fatty acids

NIR news ◽  
2018 ◽  
Vol 29 (6) ◽  
pp. 13-19 ◽  
Author(s):  
Krzysztof B Beć ◽  
Justyna Grabska
Keyword(s):  
Fatty Acids ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Infrared Region ◽  
Quantum Mechanical ◽  
Long Chain Fatty Acids ◽  
Near Infrared Spectra ◽  
Technical Article ◽  
Long Chain ◽  
Chain Fatty Acids

Exact and in-depth interpretation of near-infrared spectra has often appeared problematic in any case stepping beyond the simplest molecules. The inherent complexity of near-infrared spectra due to the abundance of combination modes and the resulting extensive band overlay frequently limits our comprehension of the spectral bands to vague wavenumber regions in which certain modes likely appear. Coincidently, quantum mechanical simulation of spectra which could offer momentous support in solving such problems has rather been rare in the case of near-infrared region due to practical limitations. Recent years have seen a trending development of accurate and affordable methods of near-infrared spectra simulation. A trend in modelling increasingly complex molecules can be noticed reaching even fairly large biomolecules. In this technical article we overview the most recent accomplishments in the field on the example of long-chain fatty acids and their cyclic dimers, which extend beyond 100 atoms.

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