The Raman spectrum of kaolinite #9 at 21°C

1986 ◽  
Vol 64 (2) ◽  
pp. 285-294 ◽  
Author(s):  
K. H. Michaelian
Keyword(s):  
Raman Spectrum ◽  
New Mexico ◽  
Infrared Spectra ◽  
Lattice Vibration ◽  
Raman Band ◽  
Vibrational Modes ◽  
Simple Description ◽  
Longitudinal Splitting ◽  
Surface Hydroxyl ◽  
Existing Data

The Raman spectrum of kaolinite #9, a layer silicate of composition Al2Si2O5(OH)4 from Mesa Alta, New Mexico, USA, is reported and compared to previously published Raman and infrared spectra, as well as calculated lattice vibration frequencies, of other kaolinite samples. In the OH stretching region, a Raman band is observed at 3684 cm−1, a frequency which is generally unknown in infrared spectra of kaolinite. The two most likely origins of this band are (a) uncoupled inner-surface hydroxyl stretching, and (b) transverse/longitudinal splitting involving the 3695 cm−1 band, which occurs in both Raman and infrared spectra of kaolinite. The existing data do not conclusively show which of these explanations is correct. In the lattice vibration region, most of the observed Raman bands of kaolinite #9 have been tentatively assigned by comparison with published frequency calculations and existing assignments of infrared spectra of various kaolinites. The descriptions of many of the vibrational modes are approximate, partly because extensive mixing of vibrations makes a simple description of them impossible.

scholarly journals Resonanz-Raman-Effekt von Thiocyanatkomplexen einiger Übergangsmetalle

1970 ◽  
Vol 25 (10) ◽  
pp. 1394-1400 ◽  
Author(s):  
W. Krasser ◽  
H. W. Nürnberg
Keyword(s):  
Raman Spectrum ◽  
Infrared Spectra ◽  
High Intensity ◽  
High Frequency ◽  
Resonance Raman ◽  
Ammonium Salts ◽  
Iron Cobalt ◽  
Decay Products ◽  
Thiocyanate Complexes ◽  
Resonance Raman Spectra

Abstract The thiocyanates of the transition metals iron, cobalt, copper as well as of rhenium and of tech-netium appear in solution as strongly coloured complexes. The resonance raman bands in the sol-vent acetonitrile are investigated. To achieve an unambiguous identification the infrared spectra were recorded too. The change in position and structure of the acetonitrile bands indicates strong complexation of iron, cobalt and copper with acetonitrile, thus indicating the existence of mixed acetonitrile-thiocyanate complexes. The resonance raman spectra of the rhenium-and technetium-thiocyanates present as tetramethyl ammonium salts show however no raman-and infrared-bands of complexed acetonitrile molecules.In the raman spectrum of the thiocyanates of iron, cobalt and copper mainly the totally sym-metric C≡N, S-C, Me-S and Me-N valence vibrations are observed, among which the S-C vibration shows a remarkably high intensity. Besides, a series of bands is obtained which is inter-preted partly as caused by decay products, and partly as bands of complexed acetonitrile. The thiocyanates of rhenium and of technetium show the three possible valence vibrations only. The high frequency of the S-C valence indicates the N-coordination of the thiocyanate group.

A Raman and infrared spectroscopic study of triethylenediamine (DABCO) and its protonated forms

1988 ◽  
Vol 66 (5) ◽  
pp. 1249-1257 ◽  
Author(s):  
David A. Guzonas ◽  
Donald E. Irish
Keyword(s):  
Raman Spectrum ◽  
Spectroscopic Study ◽  
Infrared Spectra ◽  
Infrared Spectroscopic Study ◽  
Protonated Forms ◽  
Infrared Spectroscopic ◽  
Vibrational Bands

The Raman and infrared spectra of DABCO have been measured as a function of the pH, and the vibrational bands of the two protonated forms of DABCO have been tabulated and assigned. The frequencies of several of the Raman bands were found to exhibit substantial shifts upon protonation, and the appearance of the Raman spectrum in the region between 900 and 1100 cm−1 in particular shows differences which can be used to differentiate between the three forms of DABCO. The values of the two pKa's were determined from the intensity versus pH plots for the three species.

Identification of the Vibrational Modes in the Far-Infrared Spectra of Ruthenium Carbonyl Clusters and the Effect of Gold Substitution

2014 ◽  
Vol 53 (9) ◽  
pp. 4340-4349 ◽  
Author(s):  
Trystan Bennett ◽  
Rohul H. Adnan ◽  
Jason F. Alvino ◽  
Vladimir Golovko ◽  
Gunther G. Andersson ◽  
...  
Keyword(s):  
Infrared Spectra ◽  
Far Infrared ◽  
Vibrational Modes ◽  
Carbonyl Clusters ◽  
Ruthenium Carbonyl ◽  
Ruthenium Carbonyl Clusters ◽  
Far Infrared Spectra

scholarly journals Analysis of functional groups in atmospheric aerosols by infrared spectroscopy: sparse methods for statistical selection of relevant absorption bands

2016 ◽  
Vol 9 (7) ◽  
pp. 3429-3454 ◽  
Author(s):  
Satoshi Takahama ◽  
Giulia Ruggeri ◽  
Ann M. Dillner
Keyword(s):  
Infrared Spectra ◽  
Atmospheric Aerosols ◽  
Quantitative Prediction ◽  
Calibration Model ◽  
Vibrational Modes ◽  
Aerosol Composition ◽  
Absorption Bands ◽  
Calibration Models ◽  
Ft Ir ◽  
Selection Of

Abstract. Various vibrational modes present in molecular mixtures of laboratory and atmospheric aerosols give rise to complex Fourier transform infrared (FT-IR) absorption spectra. Such spectra can be chemically informative, but they often require sophisticated algorithms for quantitative characterization of aerosol composition. Naïve statistical calibration models developed for quantification employ the full suite of wavenumbers available from a set of spectra, leading to loss of mechanistic interpretation between chemical composition and the resulting changes in absorption patterns that underpin their predictive capability. Using sparse representations of the same set of spectra, alternative calibration models can be built in which only a select group of absorption bands are used to make quantitative prediction of various aerosol properties. Such models are desirable as they allow us to relate predicted properties to their underlying molecular structure. In this work, we present an evaluation of four algorithms for achieving sparsity in FT-IR spectroscopy calibration models. Sparse calibration models exclude unnecessary wavenumbers from infrared spectra during the model building process, permitting identification and evaluation of the most relevant vibrational modes of molecules in complex aerosol mixtures required to make quantitative predictions of various measures of aerosol composition. We study two types of models: one which predicts alcohol COH, carboxylic COH, alkane CH, and carbonyl CO functional group (FG) abundances in ambient samples based on laboratory calibration standards and another which predicts thermal optical reflectance (TOR) organic carbon (OC) and elemental carbon (EC) mass in new ambient samples by direct calibration of infrared spectra to a set of ambient samples reserved for calibration. We describe the development and selection of each calibration model and evaluate the effect of sparsity on prediction performance. Finally, we ascribe interpretation to absorption bands used in quantitative prediction of FGs and TOR OC and EC concentrations.

scholarly journals Temperature-Dependent Raman Spectroscopic Study of the Double Molybdate KBi(MoO4)2

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5453
Author(s):  
Min Wang ◽  
Changhao Wang ◽  
Jian Wang ◽  
Liming Lu ◽  
Xiaoye Gong ◽  
...  
Keyword(s):  
High Temperature ◽  
Raman Spectra ◽  
Monoclinic Phase ◽  
Raman Band ◽  
Vibrational Modes ◽  
Temperature Dependent ◽  
Raman Spectroscopic ◽  
Thermal Stability Of ◽  
Good Agreement

In situ high-temperature Raman spectra of polycrystalline KBi(MoO4)2 were recorded from room temperature to 1073 K. Thermal stability of the monoclinic KBi(MoO4)2 was examined by temperature-dependent XRD. The monoclinic phase transformed into the scheelite tetragonal structure at 833 K, and then to the monoclinic phase at 773 K. Quantum chemistry ab initio calculation was performed to simulate the Raman spectra of the structure of KBi(MoO4)2 high-temperature melt. The experimental Raman band at 1023 K was deconvoluted into seven Gaussian peaks, and the calculated results were in good agreement with the experimental data. Therefore, the vibrational modes of Raman peaks of molten KBi(MoO4)2 were assigned. It was confirmed that the isolated structure of [Bi(MoO4)2]− monomer, consisting of Mo6+ centers and Bi3+ sub-centers connected by edge-sharing, mainly exists in the melt of KBi(MoO4)2.

First-Principles Study of Structural and Vibrational Properties of α-SiO2 under Pressure

2015 ◽  
Vol 775 ◽  
pp. 191-196
Author(s):  
Xiao Wei Lei ◽  
Yong Song ◽  
Kuo Yang ◽  
Hui Zhao
Keyword(s):  
High Pressure ◽  
Perturbation Theory ◽  
Infrared Spectra ◽  
First Principles ◽  
Linear Response ◽  
Density Functional ◽  
Vibrational Properties ◽  
Vibrational Modes ◽  
Density Functional Perturbation Theory ◽  
Good Agreement

Using first principles approach, we present the structural, vibrational and dielectric properties of α-SiO2. The calculations have been carried out within the density functional perturbation theory and linear response formalism using the norm-concerving pseudopotentials and a plane wave basis. All the vibrational modes identified are in good agreement with experiment. The calculated infrared spectra are also in good agreement with available experimental results both for the positions and the intensities of the main peaks. We find that the modes Eu7 and A2u4 splits in two respectively at high hydrostaticpressures. Then we calculate the infrared spectra under high pressure of different orientations. The vibrational modes in different phase transitions are reported and discussed respectively.

Vibrational spectroscopic studies and normal coordinate analyses of TiCl4 donor-acceptor complexes

1974 ◽  
Vol 27 (9) ◽  
pp. 1855 ◽  
Author(s):  
RP Cooney ◽  
DB Fraser
Keyword(s):  
Raman Spectrum ◽  
Spectral Data ◽  
Infrared Spectra ◽  
Spectroscopic Studies ◽  
Normal Coordinate ◽  
Laser Raman ◽  
Laser Raman Spectra ◽  
Donor Acceptor ◽  
Nitrogen Heteroatom ◽  
Octahedral Configuration

Laser Raman spectra and infrared spectra are reported for TiCl4,2MeCN, TiCl4,2PhCN, TiCl4,2py, TiBr4,2MeCN. For purposes of comparison the Raman spectrum of SnC14,2Ph3P has been recorded and assigned. Analysis of data indicates that a cis octahedral configuration is adopted by the TiC14,2L complexes and a trans configuration by SnCl4,2Ph3P. In addition a new complex, 3TiC14,4cpy, has been prepared and spectral data indicate the ligand bonds through its nitrogen heteroatom. Normal coordinate analyses and Urey-Bradley force constants are reported for TiC14,2MeCN and TiCl4,- 2PhCN.

Adsorption of water and 18O exchange of surface hydroxyl groups on silica

1970 ◽  
Vol 48 (15) ◽  
pp. 2454-2456 ◽  
Author(s):  
B. A. Morrow ◽  
A. Devi
Keyword(s):  
Infrared Spectroscopy ◽  
Infrared Spectra ◽  
Sample Temperature ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Silanol Groups ◽  
Surface Hydroxyl Groups ◽  
Adsorption Of Water ◽  
Exchange Technique

Infrared spectroscopy has been used to show that the surface hydroxyl groups on highly dehydrated silica will exchange with 18O-labeled water. The degree of exchange depends on the sample temperature and is a maximum at about 400 °C, where approximately 65% of the silanol groups contain 18O. The use of the 18O exchange technique for assigning surface-adsorbate stretching modes is illustrated by considering the infrared spectra of BF3 chemisorbed on silica.

Infrared Spectra of Crystalline Acetic Acid, a Hydrogen-Bonded Polymer

1977 ◽  
Vol 31 (2) ◽  
pp. 110-115 ◽  
Author(s):  
P. F. Krause ◽  
J. E. Katon ◽  
J. M. Rogers ◽  
D. B. Phillips
Keyword(s):  
Hydrogen Bonding ◽  
Acetic Acid ◽  
Infrared Spectra ◽  
Group Analysis ◽  
Structural Models ◽  
Factor Group ◽  
Vibrational Modes ◽  
Cryogenic Temperatures ◽  
Polymeric Chains ◽  
Hydrogen Bonded

The polarized infrared spectra of crystalline acetic acid and two of its deuterated derivatives, CH3COOD and CD3COOD, have been recorded from 400 to 4000 cm−1 at cryogenic temperatures. The spectroscopic results have been interpreted on the basis of a factor group analysis based on two structural models: a crystallographic cell composed of four interacting monomer units some of whose vibrational modes are highly perturbed by hydrogen bonding and a unit cell composed of two noninteracting acetic acid chains. The results are discussed in terms of possible interactions between the hydrogen-bonded acetic acid polymeric chains.

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