Neil T. McDevitt

Infrared absorption study of metal oxides in the low frequency region (700-240 cm−1)

Abstract The characteristic frequencies of oxides of 52 metals have been studied in the region 700-240 cm−1. Data for oxides of metals of different valence states and the frequencies of polymorphic forms of several oxides are presented. A particle size of 10 μ or smaller was found to give the best representative spectrum.

Infrared Lattice Spectra of Cubic Rare Earth Oxides in the Region 700 to 50 cm −1

The infrared lattice spectra from 700 to 50 cm−1 of eight cubic rare earth oxides are reported. It is evident from these data that the crystal structure determines the frequency position, and clearly shows the effect of the lanthanide contraction in this series of compounds.

Characteristic group frequencies of bromo and iodoalkanes in the cesium bromide region

Abstract The infrared spectra of 74 normal and branched bromo and iodoalkanes have been recorded and studied in the range of 667-286 cm−1. It was found that the number and position of the frequencies characteristic of the CX stretching vibration are dependent on the rotational isomers present as well as the structure of the alkyl substituents in the vicintiy of the CX group. Conformational structures and representative spectra are presented along with correlation charts which list the CX stretching vibration for various primary, secondary and tertiary bromo and iodoalkanes.

Infrared Lattice Spectra of Rare-Earth Aluminum, Gallium, and Iron Garnets

The infrared lattice spectra of a large number of rare-earth garnets have been recorded. Of the seventeen predicted lattice modes, we observed 15 for the aluminum series, 12 for the gallium, and 10 for the iron. A set of three bands in the high-frequency region of each spectrum has been assigned to the motion of the oxygen anions bonded to the rare-earth cation. The lowest-frequency bands in each spectrum have been assigned to the translational motions of the rare-earth ion. All of the frequencies were assigned to external motions of the crystal lattice.

Infrared‐Absorption Spectra of Chloro‐, Bromo‐, and Iodoalkanes in the 400‐to‐100‐cm−1 Region

The infrared‐absorption spectra of 18 haloalkanes have been studied and the carbon—halogen bending vibration assigned for each molecule. The effect of rotational isomerism on this vibration was determined. The low‐frequency torsional modes have also been assigned. Solid‐state studies contributed to the support of the assignments and made it possible to determine rotational effects.

The character of low frequency (250-40 cm−1) raman bands from organic liquids and their comparison to far infrared absorption

Abstract The low frequency Raman scattering of 28 aromatic compounds has been measured in the liquid phase. There was found to be no correlation between the Raman scattering and the observed low frequency infrared absorption found in these liquids. Attempts to relate the Raman scattering to mass effects and dipole moments failed to show any apparent correlation. The Raman scattering and infrared absorption are interpreted as arising from the formation of a transient complex between two or more molecules. The Raman scattering arises from the symmetrical vibration or translational libration of the complex, while the low frequency infrared absorption is the direct conse- quence of a hindered rotational vibration of the molecule, in this case, the benzene ring in the complex.

The vibrational spectra of propynoic acid and sodium propynoate

Abstract The vibrational spectra of propynoic acid and sodium propynoate are reported. These include both the infrared and Raman spectra in the region 4000-100 cm −1 . Partial spectra of the deuterium-substituted compounds are also reported. The fundamental frequencies have been assigned in both compounds.

Infrared Lattice Spectra of Rare-Earth Stannate and Titanate Pyrochlores

The ir lattice spectra of six rare-earth stannates and six rare-earth pyrochlores have been recorded. A factor-group analysis has been performed on the Oh7–Fd3m space group. The analysis predicts seven F1u ir-active modes, and A1g, Eg, and 4 F2g Raman-active modes. All the 7 predicted F1u transverse optic modes have been observed. The highest-frequency band in each spectrum correlates with the unit-cell volume of the crystal; however, the stannate data appear to be anomalous with the previously reported rare-earth garnet data.

Contamination of KBr Pellets by Plastic Mixing Vials

Potassium bromide is widely used as a matrix material in infrared spectroscopy (1). In fact, the KBr pressed pellet technique has almost completely supplanted the mineral oil-mull technique in some laboratories. The KBr method has several inherent advantages such as absence of interfering absorption bands, reproducible concentrations, and use of small 1-2 mg. samples. However, as with any method of sample preparation, the KBr technique has limitations and difficulties. For instance, unusual or misleading effects have been noted in this technique due to grinding (2), pressing (3), and interactions between the solid sample and matrix (4,5). The difficulty of preparing a homogeneous sample seems to have been solved by the use of the mechanical vibrator (6,7).

The Use of the Short Beam Shear Test Method on Metal-to-Metal Adhesive Bonds

Abstract : Most literature studies show that failure of an adhesive joint occurs, in general, in the region of the adhesive-oxide interface. The three major mechanical tests used today usually provide information on only the bulk adhesive. This paper presents the use of the short beam shear test as a means of loading the adhesive-oxide interface with as much shear force as possible in order to determine any subtle changes that may occur in this area during environmental testing. (Author)