Applications of Infrared Methods in the Structural Examination of Synthetic Rubber

1946 ◽  
Vol 19 (4) ◽  
pp. 1113-1123 ◽  
Author(s):  
J. E. Field ◽  
D. E. Woodford ◽  
S. D. Gehman
Keyword(s):  
Absorption Spectra ◽  
Organic Molecules ◽  
Normal Modes ◽  
Structural Variations ◽  
Structural Examination ◽  
Absorption Bands ◽  
Synthetic Rubber ◽  
Modes Of Vibration ◽  
Long Chain

Abstract Infrared absorption spectra have been long recognized as a convenient means for studying the structure of organic molecules. The interpretations of the spectra are based on the energy interactions of the molecule and the radiations which arise from the vibration of the constituent atoms and molecular rotations. For simple or highly symmetrical molecules, the determination of the normal modes of vibration and the calculation of the absorbing frequencies are relatively simple and straightforward. For more complicated organic molecules, this becomes increasingly difficult because with each additional atom, the number of degrees of freedom is increased by three and the determination of the normal modes of vibration becomes practically impossible. However, interpretations can be made to a useful extent through empirical comparisons with the absorption spectra of simpler known structures. The data that have been accumulated by investigators in this field have made it possible to assign rather definite absorption frequencies to some of the chemical linkages and functional groups. These correlations which have appeared in numerous places in the literature are partially reproduced in Table I. Organic compounds generally have strong absorption bands below 1300 cm−1, to which few definite assignments can be made with certainty because the vibrations of many of the atoms of the molecule may be involved rather than a specific part of it. It is clear that such empirical relationships must be relied upon in studying the structural variations of the long chain, complex molecules which occur in butadiene and isoprene polymers and copolymers and other synthetic rubbers. This procedure has been applied to determine the effects of oxidation and of variations in monomers and polymerizing conditions on the structure of synthetic rubber. It is practically certain that physical deficiencies of synthetic rubber are due principally to the structure of the long chain molecules rather than to the chemical nature of the monomers used.

Free Vibration of Continuous Skin-Stringer Panels

1960 ◽  
Vol 27 (4) ◽  
pp. 669-676 ◽  
Author(s):  
Y. K. Lin
Keyword(s):  
Free Vibration ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Normal Modes ◽  
Time Dependent ◽  
Experimental Measurements ◽  
Structural Configuration ◽  
Modes Of Vibration ◽  
Fuselage Skin

The determination of the natural frequencies and normal modes of vibration for continuous panels, representing more or less typical fuselage skin-panel construction for modern airplanes, is discussed in this paper. The time-dependent boundary conditions at the supporting stringers are considered. A numerical example is presented, and analytical results for a particular structural configuration agree favorably with available experimental measurements.

scholarly journals The normal vibrations of carbonate and nitrate ions

1931 ◽  
Vol 134 (823) ◽  
pp. 265-277 ◽  
Keyword(s):  
Raman Spectrum ◽  
Raman Spectra ◽  
Raman Effect ◽  
Normal Modes ◽  
Potassium Nitrate ◽  
Nitrate Ions ◽  
Carbonate Ion ◽  
Infra Red ◽  
Modes Of Vibration

When the Raman effect was first discovered, it was believed that every line in the Raman spectrum referred to some characteristic vibration of the scatter­ing molecule. Later the tendency was to regard the lines as due to transitions between states of vibration of the molecule, so that the energies corresponded not to energies of vibration directly, but to differences in the energy of vibra­tion of two different modes. It is now realised that the infra-red spectrum of a substance and the Raman spectrum which it scatters give complementary information. Certain modes of vibration are represented solely in the infra­red spectrum, others are found only in the Raman spectrum, while others may appear in both spectra. Quite early a rough criterion on the basis of symmetry was put forward by Schaefer, for the determination of whether or not a particular vibration was to be expected in the Raman effect. Recently a selection rule has been formulated by Placzek; no vibration will appear as a fundamental in the Raman effect if it is such that any symmetrical operation upon it can change the signs of the displacements of the normal co-ordinates, without altering the energy. It is clear that a knowledge of the normal modes of vibration of the molecule under discussion must precede the application of any such rule, and it is the purpose of the present communication to discuss the normal modes of vibration of the carbonate and nitrate ions. In 1929 the writer showed that it was possible to obtain Raman spectra from powdered crystals, and the discovery was made when using powdered crystals of potassium nitrate. The method was applied first to carbonates and nitrates, so it became of interest to attempt to fix the structure of the anions of these salts by means of the Raman spectra combined with the infra-red data. In what follows the carbonate ion will first be dealt with in some detail, and then the nitrate ion can be treated summarily owing to the similarity of structure of the two ions.

scholarly journals Bulk Solubility and Speciation of Plutonium(VI) in Phosphate-Containing Solutions

1992 ◽  
Vol 294 ◽  
Author(s):  
H. T. Weger ◽  
S. Okajima ◽  
J. C. Cunnane ◽  
D.T Reed
Keyword(s):  
Absorption Spectra ◽  
Accurate Determination ◽  
Absorption Bands ◽  
Initial Ph ◽  
Colloid Formation

ABSTRACTThe solubility and speciation of Pu(VI) with phosphate is being investigated to determine the ability of phosphate to act as an actinide getter. In the initial studies performed, solubility was approached from oversaturation at an initial pH = 4, 10 and 13.4. Absorption spectra were recorded, the solution filtered, and the filtrate analyzed for Pu content. Absorption spectra were obtained at varying phosphate concentrations, and at pH of 2.7 to 11.9. The effect of complexation on the 833 nm Pu(VI) band was characterized. Evidence for three phosphate complexes was obtained for pH < 10, which have absorption bands at 842, 846 and 849 nm. Evidence for colloid formation was observed, but is not conclusive. The possible presence of colloids prevented an accurate determination of true solubility. A concentration of 10−5 to 10−6M Pu(VI) was measured in solutions at pH ≤ 10 that was filtered with a 50 nm filter. Pu(VI)-phosphate complexes predominated at pH ≤ 11.6. At higher pH, however, only hydrolyzed Pu(VI) was detected. At pH = 12, the concentration of Pu(VI) was as high as 10−4M.

Absorption of oxygen in silicon in the near and the far infrared

1970 ◽  
Vol 317 (1528) ◽  
pp. 133-152 ◽  
Keyword(s):  
Infrared Spectrum ◽  
Isotope Shift ◽  
Normal Modes ◽  
Far Infrared ◽  
Uniaxial Stress ◽  
Absorption Bands ◽  
Clear Cut ◽  
Oxygen Complex ◽  
Anharmonic Potential ◽  
Modes Of Vibration

Previous work on oxygen in silicon has shown that oxygen dissolves interstitially in silicon forming a complex which may be approximately described as Si 2 O. Absorption bands of Si : O occur at 517, 1136 and 1203 cm -1 and these have been assigned by earlier authors to the v 2 (symmetric bending), v 3 (antisymmetric stretch) and v 1 (symmetric stretch) normal modes of vibration of Si 2 O. The present investigation confirms the v 3 origin of the 1136 cm -1 band (the well-known 9 μ m band) but we disagree with the earlier assignments of the 517 and 1136 cm -1 bands. The results reported here are relevant to organic siloxanes. We have extended the investigation of Si : O into the far infrared and we find sharp absorption lines at 29.3, 37.8, 43.3 and 49.0 cm -1 which we have assigned to the v 2 mode of Si 2 O. The isotope shift due to l8 O has been observed in the far infrared spectrum. Effects of uniaxial stress on the 29.3 cm -1 line have been investigated and are found to be consistent with the assignment to the v 2 mode. The main features of the far infrared spectrum are accounted for with a simple anharmonic potential which ignores coupling of the Si 2 O to the crystal lattice. We have investigated effects of uniaxial stress on the 517, 1136 and 1203 cm -1 bands of Si 2 O. Our stress results for the 1136 cm -1 band are consistent with the earlier v 3 assignment. Using our normal mode description, we conclude that the 1203 cm -1 band is a combination band involving v 3 and v 2 excitations. We have not been able to give a clear cut assignment to the 517 cm -1 band, but we suggest that v 1 type excitation may be involved. The appendix describes the stress splitting of the 836 cm -1 band of the silicon A centre in electron irradiated Si : O and our results confirm an earlier model for this centre. In all cases investigated here, the stress splittings arise from raising the orientational degeneracy of the oxygen complex.

Champ de force de valence et modes normaux de vibration de la glycylglycine et du monochlorhydrate monohydrate de glycylglycine

1974 ◽  
Vol 52 (14) ◽  
pp. 2590-2602 ◽  
Author(s):  
Christian Destrade ◽  
Eliane Dupart ◽  
Monique Joussot-Dubien ◽  
Chantal Garrigou-Lagrange
Keyword(s):  
Solid State ◽  
Force Field ◽  
Vibrational Spectra ◽  
Molecular Conformation ◽  
Normal Modes ◽  
Valence Force ◽  
Valence Force Field ◽  
Modes Of Vibration

The valence force field and normal modes of vibration of α-glycylglycine have been calculated using the vibrational spectra of ten isotopic derivatives, selectively labeled with deuterium or nitrogen-15. It is shown that this force field permits the determination of the frequencies of glycylglycine-hydrochloride in the solid state, despite a structure very different from that of the zwitterion. The agreement is particularly satisfying for those modes of vibration most sensitive to molecular conformation. It is thus possible to use this type of calculation to determine the conformation of an oligopeptide.

The Determination of Vibration Modes

1949 ◽  
Vol 53 (468) ◽  
pp. 1095-1099
Author(s):  
N. F. Harpur
Keyword(s):  
Normal Mode ◽  
Degrees Of Freedom ◽  
Normal Modes ◽  
Dynamic Loads ◽  
Vibration Modes ◽  
Resonance Modes ◽  
Modes Of Vibration

At some stage in the design of every aeroplane it is necessary to estimate or to measure the resonance modes of vibration. This has not always been the case, but the problems of flutter, control reversal and dynamic loads have increased in importance as speeds have risen. Nowadays, it is an airworthiness requirement that these effects be considered and the aircraft made safe for all conditions of flight. A knowledge of the normal modes of vibration is essential for all accurate estimates of these aeroelastic effects.Taking flutter as an example, the technique of flutter investigations consists of first determining which combinations of the various possible degrees of freedom are liable to excite dangerous oscillations. Typical degrees of freedom for a wing are bending and twist in each normal mode, aileron deflection and tab deflection; for a tailplane and elevator we might consider tailplane bending or twist, elevator deflection, tab deflection, fuselage bending and twist, and pitching of the whole aeroplane.

Dithiolate Mixed with Diimine and it's Metal Effects on Sensors

2014 ◽  
Vol 1021 ◽  
pp. 52-55
Author(s):  
Yong Hui Jia ◽  
Chao Xu
Keyword(s):  
Energy Level ◽  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Spectra ◽  
Electronic Absorption Spectra ◽  
Orbital Energy ◽  
Absorption Bands ◽  
The Relationship ◽  
Orbital Energy Level

Determination of the two Maleinitriledithiolate • phenanthroline-5 ,6-dione Lynn mixed copper (II), zinc (II) complexes MLL' (L=mnty, 1,2 twelve dicyanoethylene-1,2 - thiol ion L '= phen-5, 6-dione, l, 10 - phenanthroline-5 ,6-one o) amine in dimethy-l phthalate (DMF), acetone (Acet.) and chloroform (HCli) electronic absorption spectra corresponding to transitions studied the relationship between the absorption bands in the electronic spectra associated molecular orbital energy level diagram to explore their photographic oxidation characteristics in DMF.

scholarly journals Luminescent determination of residues of trazodon hydrochloride and melatonin after cleaning pharmaceutical equipment

2019 ◽  
pp. 73-81
Author(s):  
O. D. Voitiuk ◽  
A. V. Yegorova ◽  
Yu. V. Scrypynets ◽  
S. N. Kashutskуy ◽  
V. P. Antonovich
Keyword(s):  
Absorption Spectra ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Xenon Lamp ◽  
Excitation Spectra ◽  
Absorption Bands ◽  
Limit Of Quantitation ◽  
Trazodone Hydrochloride

A prerequisite for ensuring the quality of medicines is their production in accordance with the rules of GMP (Good Manufacturing Practice for Medicinal Products), one of the most important requirements of which is equipment cleaning. In many cases, the same equipment is used in the production of various preparations. Therefore, to prevent contamination of each of the following drugs, the previous one, it is very important to carry out an effective equipment cleaning procedure with a mandatory assessment of its purity. The purpose of this study was to develop simple, express, selective methods for luminescent determination of residual quantities of APIs of trazodone hydrochloride (TG) and melatonin (MT) in washes to control the completeness of their removal when cleaning process equipment. The excitation and luminescence spectra were recorded using a Cary Eclipse "Varian" spectrofluorimeter (Australia) with a xenon lamp 150 W. Electronic absorption spectra were recorded on a UV-2401 PC spectrophotometer «Shimadzu» (Japan). The electronic absorption spectra of TG and MT have absorption bands in the UV spectral region. It was established experimentally that the excitation spectra of TG and MT are similar to their absorption spectra (λex = 318 nm (TG) and λem = 274 nm (MT)). The effect on the luminescence intensity of TG and MT of methanol, ethanol, acetonitrile, dimethylformamide, dimethylsulfoxide, propanol (50 v/v) was studied. It is established that the maximum luminescence is observed in water. The methods were validated according to the following parameters: specificity, linearity, accuracy, limit of quantitation. The degree of extraction of trazodone hydrochloride and melatonin from applicators and surfaces of pharmaceutical equipment is more than 90%. The developed methods can be recommended for determining the residual amounts of trazodone hydrochloride and melatonin while monitoring the quality of the cleaning of pharmaceutical equipment.

Structures of Na0.74WO3

2003 ◽  
Vol 59 (5) ◽  
pp. 584-587 ◽  
Author(s):  
C. N. W. Darlington ◽  
J. A. Hriljac ◽  
K. S. Knight
Keyword(s):  
Normal Modes ◽  
Stable Phase ◽  
Cubic Phase ◽  
Temperature Phase ◽  
Modes Of Vibration ◽  
Diffraction Patterns ◽  
First Time ◽  
Low Temperature Phase ◽  
The Ideal

The structures of the four phases exhibited by Na0.74WO3, sodium tungstate, with a change in temperature have been refined from powder diffraction patterns obtained on the high-resolution powder diffractometer (HRPD), ISIS, Rutherford Appleton Laboratory, England. At temperatures above 430 K, the stable phase has the ideal perovskite structure, with space group Pm\bar 3m (No. 221). Below that temperature, the octahedra are tilted about pseudocubic 〈100〉 directions; the tilts are produced by the condensation of the normal modes of vibration of the octahedra in the high-temperature cubic phase. Using Glazer's notation, the tilt system undergoes the following sequence:a^+a^+a^+ \buildrel {\rm 293\, K} \over \longrightarrow a^+a^+a^0 \buildrel {\rm 343\, K} \over \longrightarrow a^0a^0a^+ \buildrel {\rm 430\, K} \over \longrightarrow a^0a^0a^0 .The structural refinements presented here confirm the sequence of the transitions first proposed by Clarke [(1977). Phys. Rev. Lett. 39, 1550–1553]. This is the first time that a structure determination of a perovskite with the tilt system a + a + a 0 has been reported in the literature. In addition, we evaluate the weights, or importance, of the condensed modes in each low-temperature phase.

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