Raman spectroscopic studies on structure I and structure IItrimethylene oxide hydrate

2005 ◽  
Vol 83 (9) ◽  
pp. 941-949 ◽  
Author(s):  
S Subramaniam ◽  
M J Lance ◽  
C J Rawn ◽  
B C Chakoumakos ◽  
A J Rondinone
Keyword(s):  
Raman Spectra ◽  
Variable Temperature ◽  
Spectroscopic Studies ◽  
Host Lattice ◽  
Vibrational Modes ◽  
Cage Structure ◽  
Raman Spectroscopic ◽  
Oxide Hydrate ◽  
Wave Numbers ◽  
Trimethylene Oxide

Raman spectra were collected from structure I (sI) and structure II (sII) trimethylene oxide (TMO) hydrates at various temperatures and used to assign the vibrational modes, investigate the ordering of TMO molecules inside the cage structure, and to determine possible interactions between the guest and the host lattice. Only Raman spectra from sI hydrate could be analyzed since the low concentration of TMO prevented sII peaks from being resolved. Comparison of the Raman spectra of liquid, solid, and enclathrated TMO (sI) showed Raman shifts to higher wave numbers for the enclathrated TMO; mainly among the ring modes. The ring and (or) skeletal modes around 930 cm–1 and the asymmetric CH2 stretching mode around 2970 cm–1, showed shifts greater than 10 cm–1. These observed changes are interpreted on the basis of the "loose-cage – tight-cage" model, which interprets the shift as arising from strain induced by the hydrate cage on the guest TMO molecules in the 62 cages. In addition, variable temperature Raman studies, in the temperatures ranging from 103 to 203 K, showed no evidence of ordering and (or) reorientation of host molecules. PACS No.: 78.30.-j

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.

Raman Spectroscopic Studies of the Vulcanization of Rubbers. III. Studies of Vulcanization Systems Based on 2-Mercaptobenzothiazole

1972 ◽  
Vol 45 (1) ◽  
pp. 173-181 ◽  
Author(s):  
M. M. Coleman ◽  
J. R. Shelton ◽  
J. L. Koenig
Keyword(s):  
Raman Spectra ◽  
Raman Line ◽  
Lauric Acid ◽  
Spectroscopic Studies ◽  
Type I ◽  
Raman Spectroscopic ◽  
Major Significance ◽  
Sulfur Vulcanization ◽  
Cyclic Sulfide

Abstract The shoulder observed at approximately 440 cm−1 in Raman spectra of CB vulcanizates prepared from MBT based vulcanizing systems has been shown to consist of two components. There are Raman lines contributing at 440 cm−1 and 424 cm−1. The former is due to ZnO present as an extra-network material while the latter appears to be associated with polysulfidic structures. The Raman line at 505 cm−1 seen in extracted vulcanizates prepared from CB-MBT-Sulfur-ZnO-Lauric acid recipes does not appear to be solely due to disulfidic structures. The major contribution appears to be associated with an unsaturated cyclic sulfide and is most probably due to a structure of the type (I). If the assignment to cyclic sulfidic structures such as (I) is confirmed, it will have major significance with regard to the mechanism of accelerated sulfur vulcanization.

Electronic and Raman spectroscopic studies of copper adrenalin complexes and copper induced compounds

1976 ◽  
Vol 54 (24) ◽  
pp. 3815-3823 ◽  
Author(s):  
Mohammed S. Rahaman ◽  
Stephen M. Korenkiewicz
Keyword(s):  
Free Radical ◽  
Hydrochloric Acid ◽  
Raman Spectra ◽  
Spectroscopic Studies ◽  
Low Ph ◽  
Basic Solution ◽  
High Ph ◽  
Raman Spectroscopic ◽  
Ph Values

Electronic and Raman spectra of adrenalin–copper(II) complexes and copper catalyzed compounds have been studied. Adrenalin reacts with copper(II) ion at pH 9.2 and higher to produce a very short lived violet free radical, a brown adrenochrome, a yellow conjugated salt, indolyl-indoquinone, and melanin. Results indicate that copper does not form complexes with adrenalin in basic solution. Between pH 6.5 and 8.5 adrenalin transforms into adrenochrome in presence of copper. The adrenochrome in 1.5 N hydrochloric acid produces the conjugate salt that is produced in the solution of high pH. At low pH values, between pH 4.0 to 5.5, adrenalin forms a brown complex with copper(II). Copper is entirely chelated to the phenolic groups of the amines. The complex in 1.5 N hydrochloric acid produces a black polymeric pigment.

Infrared and Raman Spectroscopic Studies of Solid Alkali Metal Nitrites

1971 ◽  
Vol 49 (8) ◽  
pp. 1289-1295 ◽  
Author(s):  
M. H. Brooker ◽  
D. E. Irish
Keyword(s):  
Alkali Metal ◽  
Raman Spectra ◽  
Spectroscopic Studies ◽  
Infrared And Raman Spectra ◽  
Nitrite Ion ◽  
Nitrate Ion ◽  
Raman Spectroscopic ◽  
Linkage Isomerism ◽  
Vibrational Bands ◽  
Cation Size

Infrared and Raman spectra of solid LiNO2•H2O, LiNO2, NaNO2, KNO2, and CsNO2 are presented and discussed. Pronounced changes in the spectra of LiNO2•H2O during dehydration to anhydrous LiNO2 are interpreted as evidence for an ordered distribution of NO2− ions over two non-equivalent sites (akin to linkage isomerism) in anhydrous LiNO2. The frequencies of the internal modes of the nitrite ion shift to lower values with increasing cation size. Vibrational bands due to nitrate ion present as an impurity are assigned.

scholarly journals Toward a quantitative theoretical method for infrared and Raman spectroscopic studies on single-crystal electrode/liquid interfaces

2020 ◽  
Vol 11 (5) ◽  
pp. 1425-1430 ◽  
Author(s):  
Yuan Fang ◽  
Jin-Chao Dong ◽  
Song-Yuan Ding ◽  
Jun Cheng ◽  
Juan Miguel Feliu ◽  
...  
Keyword(s):  
Single Crystal ◽  
Raman Spectra ◽  
Theoretical Method ◽  
Integrated Approach ◽  
Spectroscopic Studies ◽  
Liquid Interfaces ◽  
Raman Spectroscopic ◽  
Single Crystal Electrode ◽  
Stm Images

An integrated approach for quantitatively predicting the electrochemical-infrared and electrochemical-Raman spectra and STM images of Pt(111)(2 × 2)-3CO adstructures has been developed.

The low frequency infrared and Raman spectroscopic studies of some uranyl complexes: the deformation frequency of the uranyl ion

1970 ◽  
Vol 48 (19) ◽  
pp. 3095-3097 ◽  
Author(s):  
J. I. Bullock ◽  
F. W. Parrett
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Low Frequency ◽  
Monovalent Cation ◽  
Spectroscopic Studies ◽  
Uranyl Ion ◽  
Not Given ◽  
Uranyl Complexes ◽  
Raman Spectroscopic ◽  
Deformation Frequency

A study of the low frequency vibrational spectra of compounds of the type L2UO2(NO3)2 (L = mono-dentate ligand), MUO2(NO3)3 (M = monovalent cation), and CS2UO2X4 (X = Cl or Br) has shown that the deformation frequency of the uranyl group occurs in the region 274–245 cm−1 but detailed assignments of the U—O (nitrate) frequencies are not given since it is shown that structurally related complexes do not necessarily give similar low frequency infrared (i.r.) and Raman spectra.

scholarly journals Phonons in Short-Period GaN/AlN Superlattices: Group-Theoretical Analysis, Ab initio Calculations, and Raman Spectra

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 286
Author(s):  
Valery Davydov ◽  
Evgenii Roginskii ◽  
Yuri Kitaev ◽  
Alexander Smirnov ◽  
Ilya Eliseyev ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Raman Spectra ◽  
Density Functional ◽  
Structural Characteristics ◽  
Vibrational Modes ◽  
Phonon Modes ◽  
Short Period ◽  
Group Theoretical Analysis

We report the results of experimental and theoretical studies of phonon modes in GaN/AlN superlattices (SLs) with a period of several atomic layers, grown by submonolayer digital plasma-assisted molecular-beam epitaxy, which have a great potential for use in quantum and stress engineering. Using detailed group-theoretical analysis, the genesis of the SL vibrational modes from the modes of bulk AlN and GaN crystals is established. Ab initio calculations in the framework of the density functional theory, aimed at studying the phonon states, are performed for SLs with both equal and unequal layer thicknesses. The frequencies of the vibrational modes are calculated, and atomic displacement patterns are obtained. Raman spectra are calculated and compared with the experimental ones. The results of the ab initio calculations are in good agreement with the experimental Raman spectra and the results of the group-theoretical analysis. As a result of comprehensive studies, the correlations between the parameters of acoustic and optical phonons and the structure of SLs are obtained. This opens up new possibilities for the analysis of the structural characteristics of short-period GaN/AlN SLs using Raman spectroscopy. The results obtained can be used to optimize the growth technologies aimed to form structurally perfect short-period GaN/AlN SLs.

scholarly journals Hydrogen Bonds: Raman Spectroscopic Study

2021 ◽  
Vol 22 (10) ◽  
pp. 5380
Author(s):  
Boris A. Kolesov
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Raman Spectra ◽  
Temperature Region ◽  
Vibrational Frequency ◽  
Chemical Compounds ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Proton Dynamics

The work outlines general ideas on how the frequency and the intensity of proton vibrations of X–H×××Y hydrogen bonding are formed as the bond evolves from weak to maximally strong bonding. For this purpose, the Raman spectra of different chemical compounds with moderate, strong, and extremely strong hydrogen bonds were obtained in the temperature region of 5 K–300 K. The dependence of the proton vibrational frequency is schematically presented as a function of the rigidity of O-H×××O bonding. The problems of proton dynamics on tautomeric O–H···O bonds are considered. A brief description of the N–H···O and C–H···Y hydrogen bonds is given.

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