closo-Halogenohydrohexaborate, IV Protonierung, Deuterierung und Schwingungsspektren von claso-Hexaboraten / closo-Halogenohydrohexaborate, IV Protonation, Deuteration and Vibrational Spectra of closo-Hexaborates

1988 ◽  
Vol 43 (10) ◽  
pp. 1319-1326 ◽  
Author(s):  
W Preetz ◽  
A Heinrich ◽  
J Thesing
Keyword(s):  
Activation Energy ◽  
Frequency Shift ◽  
Vibrational Spectra ◽  
High Frequency ◽  
Alkaline Solutions ◽  
Lower Symmetry ◽  
High Frequency Shift ◽  
Stretching Vibrations ◽  
Ph Dependent ◽  
Ir And Raman

The weak Brönsted acids B6H7- and XB6H6-, X = Cl, Br, I; pka : 7-4,75, are formed by protonation of B6H62- and XB6H52- respectively. The deuteration rates, evaluated from integrated IR band intensities of the BH and BD stretching vibrations, are linearly dependent on the mole fractions of the protonated species, and decrease with increasing degree of halogenation in the series Cl>Br>I. H atoms trans-positioned to halogens are exchanged 100 times more rapidly than the remaining ones. The activation energy for the H/D exchange amounts to 76 ± 1,5 kJ/mol for B6H7-. The lower symmetry of the protonated borates is evident from additional IR and Raman bands. They are distinguished from the corresponding Brönsted bases by a high frequency shift of the BH stretching vibrations in the order of 100 cm-1. Due to the pH dependent equilibrium B6H62-/B6H7- and different solubilities of the tetrabutylammonium salts, the separation of B6H62-/B12H122- mixtures is achievable. In alkaline solutions the very soluble B6H62- is present, whereas (TBA)2B12H12 precipitates quantitatively. By subsequent cautious acidification of the supernatant, insoluble (TBA)B6H7 is obtained.

Darstellung und Schwingungsspektren von Alkyl-und Rhodanohydrohexaboraten / Preparation and Vibrational Spectra of Alkyl and Rhodano Hydrohexaborates

1988 ◽  
Vol 43 (10) ◽  
pp. 1327-1331 ◽  
Author(s):  
A Heinrich ◽  
W Preetz
Keyword(s):  
Frequency Shift ◽  
Raman Spectra ◽  
Organic Solvents ◽  
Vibrational Spectra ◽  
High Frequency ◽  
Acidity Constants ◽  
High Frequency Shift ◽  
Basic Solutions ◽  
Stretching Vibrations ◽  
Ir And Raman

Treatment of B6H62- with iodoalkanes and (SCN)2 in organic solvents affords the monosubstituted protonated hexaborates RB6H6-, R = CH3, C2H5< C3H7, C4H9, C8H17 and SCN, respectively. The acidity constants of these weak Brönsted acids range for the alkylated species from 8.8 to 9.6, and for R = SCN the pka value is ~5. From basic solutions the salts Cs2RB6H5 can be precipitated, which show band patterns in the IR and Raman spectra typical for monosubstituted hydrohexaborates. The protonated compounds RB6H6- are distinguished from the corresponding Brönsted bases RB6H52- by a high frequency shift of the BH stretching vibrations in the order of 100 cm-1. For Cs2(SCN)B6H5, S coordination of SCN- is supposed because of the high frequency of νCN: 2144 cm-1.

Die Schwingungsspektren der Silylanionen (SiH3)nSiH⊖3-n und (SiD3)nSiD⊖3-n / Vibrational Spectra of the Silyl Anions (SiH3)nSiH⊖3-n and (SiD3)nSiD⊖3-n

1974 ◽  
Vol 29 (9-10) ◽  
pp. 647-653 ◽  
Author(s):  
Hans Bürger ◽  
Reint Eujen
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Negative Charge ◽  
Lone Pair ◽  
Normal Coordinate Analysis ◽  
Ir And Raman Spectra ◽  
Normal Coordinate ◽  
Normal Vibrations ◽  
Stretching Vibrations ◽  
Ir And Raman

The IR and Raman spectra of SiH3⊖, SiH3SiH2⊖, (SiH3)2SiH⊖, (SiH3)3Si⊖ and their deuterated derivatives have been recorded in HMPT and HMPT-d18 solutions. Most normal vibrations have been identified. The SiH and SiSi stretching vibrations are considerably lower than for analogous silanes and silylphosphines, ∼ 2050 and 1850-1900 cm-1 being characteristic for SiH3 and SiH⊖n groups respectively. The assignments are proved by a normal coordinate analysis, and force constants have been calculated. The negative charge is mainly localized on the trivalent Si atom and the lone pair acts repulsively rather than strengthening the SiSi bond through (p→d)π effects.

scholarly journals Комбинационное рассеяние света в эвтектическом композите InSb-MnSb

2020 ◽  
Vol 54 (4) ◽  
pp. 341
Author(s):  
И.Х. Мамедов ◽  
Д.Г. Араслы ◽  
Р.Н. Рагимов ◽  
А.А. Халилова
Keyword(s):  
Thin Films ◽  
Frequency Shift ◽  
Raman Spectra ◽  
High Frequency ◽  
Theoretical Data ◽  
Eutectic Composite ◽  
Flash Evaporation ◽  
Evaporation Method ◽  
The Matrix ◽  
High Frequency Shift

Raman spectra of bulk samples of the InSb-MnSb eutectic composite and their thin films prepared by the flash evaporation method have been studied. In the Raman spectra observed TO and LO modes at frequencies of 179.5 cm-1 and 192.4 cm-1 correspond to InSb compound and also the peaks at frequencies 122 cm-1, 127 cm-1, 167 cm-1, 211 cm-1, 245.5 cm-1 correspond to theoretical data for MnSb as is well known from literature. The TO mode in the Raman spectra for films is shifted toward lower energies (178 cm-1), but the LO mode is higher (196 cm-1). The high-frequency shift of the LO mode in the composite with compared its value for InSb is probably due to the presence of deformation at the matrix-inclusion interface, as well as the contribution by surface phonons scattering.

scholarly journals Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 909 ◽  
Author(s):  
Tamara Kondratenko ◽  
Oleg Ovchinnikov ◽  
Irina Grevtseva ◽  
Mikhail Smirnov ◽  
Oksana Erina ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Frequency Shift ◽  
High Frequency ◽  
Thioglycolic Acid ◽  
Low Frequency ◽  
Ftir Spectra ◽  
Ionic Form ◽  
Exciton Luminescence ◽  
Recombination Luminescence ◽  
High Frequency Shift

The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag 2 S/TGA QDs with exciton and recombination luminescence are differ from each other and B “freeB” TGA molecules. The ν ( S − H ) TGA peak (2559 cm − 1 ) disappears in FTIR spectra of Ag 2 S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag 2 S nanocrystals. Ag 2 S QDs passivation with TGA molecules leads to emergence ν a s (COO − ) (1584 cm − 1 ) and ν s (COO − ) (1387 cm − 1 ) peaks. It indicates TGA adsorption in ionic form. For Ag 2 S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of ν s (COO − ) peak from 1388 cm − 1 to 1359 cm − 1 and high-frequency shift of ν a s (COO − ) peak from 1567 cm − 1 to 1581 cm − 1 ; (b) change in the ratio of intensities of ν a s (COO − ) and ν s (COO − ) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag 2 S quantum dots.For Ag 2 S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7–10 cm − 1 for ν a s (COO − ) at 1567 cm − 1 and low-frequency shift of 3–5 cm − 1 for ν s (COO − ) at 1388 cm − 1 , probably caused by the interaction of thiol with Ag 2 S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag 2 S QDs. In the case of Ag 2 S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α -thiol-substituted acyl radical (S-CH 2 -CO • ) TGA.

closo-Halogenohydrohexaborate, III Schwingungsspektren der closo-Halogenohydrohexaborate XnB6H6-n2-, n = 1-5; X = Cl, Br, I / closo-Halogenohydrohexaborate, III Vibrational Spectra of the closo-Halogenohydrohexaborates XnB6H6-n2-, n = 1-5; X = Cl, Br, I

1987 ◽  
Vol 42 (3) ◽  
pp. 293-300 ◽  
Author(s):  
J. Fritze ◽  
W. Preetz
Keyword(s):  
Vibrational Spectra ◽  
Lower Energy ◽  
Weak Coupling ◽  
The Other ◽  
Geometric Isomers ◽  
Nmr Studies ◽  
First Approximation ◽  
Point Groups ◽  
Stretching Vibrations ◽  
Ir And Raman

The IR and Raman spectra of 20 different halogenohydrohexaborates, including pairs of geometric isomers of the series XnB6H6-n2-, X = Cl, Br, I; n = 1-5, have been assigned according to their point groups D4h, C4v, C3v and C2v determined previously by NMR studies. Due to weak coupling, the vibrations are treated separately to a first approximation in terms of internal B6-cage modes on one hand and modes of the substituents against the cage entity on the other hand. Disregarding the splitting by lowered symmetry, depending on the degree of halogenation, all internal modes of the B6 cluster are observed at nearly unchanged positions in the range of 450-1250 cm-1 . The B6-X stretching vibrations, however, exhibit significant shifts to lower energy with increasing mass of substituents

Vibrational spectra of aquadioxotetra; peroxodivanadates(V) M2[V2O2(O2)4(H2O)]·xH2O (M = N(CH3)4, Cs)

1990 ◽  
Vol 55 (6) ◽  
pp. 1485-1490 ◽  
Author(s):  
Peter Schwendt ◽  
Milan Sýkora
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Normal Coordinate Analysis ◽  
Force Constants ◽  
Infrared And Raman Spectra ◽  
Empirical Correlations ◽  
Normal Coordinate ◽  
Bond Lengths ◽  
Stretching Vibrations

The infrared and Raman spectra of M2[V2O2(O2)4(H2O)]·xH2O and M2[V2O2(O2)4(D2O)]·xD2O (M = N(CH3)4, Cs) were measured. In the region of the vanadium-oxygen stretching vibrations, the spectra were interpreted based on normal coordinate analysis, employing empirical correlations between the bond lengths and force constants.

Methods for improving the accuracy of frequency shift estimation in 5G NR

2021 ◽  
Author(s):  
Vladimir Sergeevich Milyutin ◽  
Eugeniy Vasilevich Rogozhnikov ◽  
Kirill Petrovskiy ◽  
Dmitriy Pokamestov ◽  
Edgar Dmitriyev ◽  
...  
Keyword(s):  
Frequency Shift ◽  
High Frequency ◽  
Communication Systems ◽  
Wide Frequency Range ◽  
Wireless Communication Systems ◽  
Frequency Synchronization ◽  
Frequency Range ◽  
Transmission Rates ◽  
Synchronization Accuracy ◽  
High Order Modulation

Abstract Frequency synchronization is a necessary operation for all wireless communication systems. Due to the wide frequency range defined for 5G NR systems, this procedure becomes critical. To ensure high transmission rates and the use of high-order modulation, up to 256 QAM for 5G communication systems, it is necessary to ensure high frequency synchronization accuracy. In this article, we have reviewed various approaches to implementing frequency synchronization and proposed, in our opinion, the most effective method for correcting the frequency shift of the signal.

Schwingungs-und Elektronenspektren der bindungsisomeren Hexakis(thiocyanato(N)-thiocyanato(S))-osmate(III) und (IV) / Vibrational and Electronic Spectra of Bond-Isomeric Hexakis(thiocyanato(N)-thiocyanato(S))osmates(III) and (IV)

1988 ◽  
Vol 43 (4) ◽  
pp. 371-381 ◽  
Author(s):  
K. Bütje ◽  
W. Preetz
Keyword(s):  
Charge Transfer ◽  
Vibrational Spectra ◽  
Near Infrared ◽  
Bathochromic Shift ◽  
Infrared Region ◽  
Hypsochromic Shift ◽  
Linkage Isomers ◽  
Near Infrared Region ◽  
Ir And Raman ◽  
Metal Ligand

AbstractWell-resolved IR and Raman spectra of the two sets of all 10 isomeric complexes [Os(NCS)n(SCN)6-n]3-/2-, n = 0-6, have been recorded. For both series, νCS(N) > νCS(S) and δNCS > δSCN; for the Os(III) complexes, vCN(N) ~ vCN(S) and vOsN ≥ vOsS while for the Os(IV) compounds, vCN(N) < vCN(S) and vOsN ~ vOsS. The vibrational spectra of the n = 0 and n = 6 members of both sets are assigned according to D3d and Oh point symmetry, respectively. For the mixed linkage isomers the band pattern is strongly influenced by pseudo-octahedral coupling wherever frequencies of N- and S-bonded groups coincide. The metal-ligand stretching region is therefore assigned according rather to pseudo-Oh, pseudo-D3d and pseudo-D4h symmetry than to D4h, C4v, C3v and C2v microsymmetry. The charge-transfer spectra of both series are similar, showing a parallel hypsochromic shift with increasing n value. Upon oxidation, a bathochromic shift of the CT bands by an average of 5400 cm-1 is observed, and the intensity increases by a factor 2-2.5. Weak absorptions in the near infrared region are assigned to intraconfigurational transitions.

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