Vibrational Spectra of 2,6-Diphenyl Pyridine, 2,2′:6′,2″-Terpyridine and Meta-terphenyl

The Raman and infrared spectra of 2,6-diphenyl pyridine, m-terphenyl and 2,2′:6′,2″-1erpyridine have been analysed as metadisubstituted benzene or pyridine molecules. Complete vibrational assignment shows that some modes in the case of internal vibrations of substituents appear in pairs. The splitting of these modes have been attributed to the in-and out-of-phase motions arising out of interaction between phenyl or pyridine rings, as the case may be. In the case of meta terphenyl and terpyridine, two probable cases of Fermi resonance have been observed.     

High-Resolution Spectra of the ^10B^18O and ^11B^18O： Rotational Analysis of the B-X Bands

Emission spectra of ^10B^18 O and ^11B^18 O isotopomers in the 230-330nm region have been investigated by means of conventional high-resolution spectroscopy. The molecules were produced in a low-pressure arc by discharging 8 Torr of mixture containing argon and oxygen 18 in the ratio of 4:1 and the spectra have been recorded using Ebert-type spectrograph. The boron needed to produce BO has been present in the system as amorphous powder with natural abundance of ^10B and ^11B. Rotational analysis of the 0, 0 and 0, 1 bands has been performed and spectroscopic constants have been extracted. The results have allowed first determination of the equilibrium rotational constants Be and De for both isotope species ^10B^18O and ^11B^18O in their lower electronic state.Assuming a linear dependence of Be on (v 1/2), the value of equilibrium distance re in the lower state has been derived.     

The Application of Infrared Spectra to Structural Problems in Copper(II) Complexes of 2,2′-Bipyridine

The infrared spectra of the complexes [Cu(bipy)₃] (C10₄)^2′ [Cu(bipy)₂] (C10₄)₂, [Cu(bipy)₂I]I, [cu(bipy)₂I] C10₄ and [Cu(bipy)(C10₄)₂] (bipy - 2,2′-bipyridine) are discussed in relation to their known or probable structures. Evidence for tetragonal distortion of [Cu(bipy)₃]₂₊ but not [Cu(phen)₃]₂₊ (phen = 1, 10-phenanthroline) is adduced.     

Infrared and Raman Spectra for Amino Group and C˭O Stretching Modes in Biomolecule 5‐Aminouracil

Abstract

Assuming planar geometry of 5‐aminouracil and C_s point group symmetry, it has been possible to assign all the 36 (25a′+11a″) normal modes of vibration. The two NH bonds of the NH₂ group appear to be non-equivalent as the NH₂ stretching frequencies and do not satisfy the empirical relation proposed for the two equivalent NH bonds of the NH₂ group due to their involvement and interaction with one hydrogen bond and the other adjacent oxygen atom of the parent molecule. The planar and nonplanar bending modes due to the C₄?O₈ bond are expected with have lower magnitude compared with those due to the C₂?O₇ bond.     

Raman Spectra of Alkali and Alkaline Earth Metal Salts of Inosine 5′-Monophosphoric Acid

Crystalline Li(I), Na(I), K(I), Mg(II), Ca(II), Sr(II), Ba(II) and Cd(II) salts of inosine 5′-monophosphoric acid, H₂(IMP), were obtained and characterized by Raman spectroscopy. Splitting of the imidazolic 1480 cm⁻¹ band was observed for the N(7)-bound Ca(IMP)·6H₂O, Ba(IMP)·6H₂O, Sr(IMP)·6H₂O and Cd(IMP)·4H₂O compounds. The Li(I), Mg(II), Ca(II) and Cd(II) ions bind directly to the phosphate group, and no direct coordination involving the carbonyl C(6)O group was observed in the compounds reported here. Some Raman spectral features in the 750–700 cm⁻¹ range seem to reflect the nucleoside structure of the inosine moiety     

Infrared Spectral Hole—Burning and Spectral Diffusion of Vibrational N—D Bands in a Disordered Tutton Salt

We have studied infrared spectral hole burning of the N-D stretching bands of NH3D^ in salt[(NH4)2Co0.25Ni0.75 (H2O)6(SO4)2] at 10K.We have observed that the spectral line broadening occurred on a logarithmic timescale,which is consistent with the theoretical prediction of a standard two-level system.The temperature of 10K is also beyond the temperature limit in previous studies on spectral diffusion.     

Vibrational Spectra of α-Pyrazinamide and 15N-α-Pyrazinamide

α-Pyrazinamide and its α-Pyrazinamide-d² as well as the ¹⁵N-isotopic derivative were synthesized with an isotopic content of 99.4% and their Raman and infrared spectra were recorded and assigned on the basis of isotopic shifts.     

Algebraic Hamiltonian for Vibrational Spectra of Stibine

An algebraic Hamiltonian, which in a limit can be reduced to an extended local mode model by Law and Duncan, is proposed to describe both stretching and bending vibrational energy levels of polyatomic molecules, where Fermi resonances between the stretches and the bends are considered. The Hamiltonian is used to study the vibrational spectra of stibine (SbH3). A comparison with the extended local mode model is made. Results of fitting the experimental data show that the algebraic Hamiltonian reproduces the observed values better than the extended local mode model.     

Super-Resolved Raman Spectra of Toluene and Toluene–Chlorobenzene Mixture

In this paper, we present a method for “super-resolved” Raman spectroscopy which improves the resolution of obtained spectra. Experimental investigations were carried out on the spectra of toluene and a toluene–chlorobenzene mixture. A tunable Fabry–Perot filter is added to the detection channel and by measuring the spectra for several states of the filter a spectrum of higher resolution can be obtained after a decoding process. We demonstrate both a reduced linewidth in the pure toluene spectra and partial separation of the two overlapping peaks in the mixture.     

Electrical Properties and Raman Spectra of BaBi1-xPbxO3

Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semiconducting range, whereas it vibrates similarly to a sine wave in the superconducting range, which is ascribed to the existence of oxygen vacancies and the function of breathing modes of Bi（Pb）O6. The temperature dependence of resistivity indicates that the electrical property of the samples is connected sensitively with the crystal structures. Raman spectra show that the specimen becomes disorder when x increases, and the critical temperature To depends not only on the deformation potential of the soft A19 mode derived from the Bi（Pb）O6 rigid rotation, but also on the energy shift of the mode.     

Vibrational Analysis of the β System of 10B18O

Ten bands of the β system (B²Σ⁺ ? X²Σ⁺) of the ¹⁰B¹⁸O molecule have been observed for the first time. The spectrum was obtained by emission spectroscopy from a low‐pressure arc, at medium dispersion, and vibrationally analyzed using isotope shift measurements. Vibrational analysis gave the constants ω_e and ω_ex_e for both electronic states involved in the transitions.     

An Overview of the High‐Pressure Vibrational Spectra of Clays and Related Minerals

Abstract

An overview of the effect of high external pressures on clays and related minerals is presented. The results show that this is an area that will welcome further investigation in the future, especially in view of the importance of clay minerals in the Earths's mantle and, possibly, even in prebiotic chemistry in the formation of amino acids and the mineralogy of the Martian surface.     

The Infrared and Raman Spectra of β-and α-Tricalcium Phosphate (Ca3(Po4)2)

Factor group analysis was applied to interpret the vibrational spectra of β-and α-tricalcium phosphate (Ca₃(PO₄)₂). The analysis predicts the number of bands formed due to the splitting of the fundamental vibrational modes of the PO₄ ^3-ion. The number of the infrared and Raman bands predicted by this analysis for the two phases are drastically different and can be ascribed to the difference in atomic arrangements in the two phases resulting in greater shielding of the PO₄ ^3-ions in the β-phase than in the α-phase. Discrepancies in the number of predicted and experimentally-observed bands can be attributed to the weak intensities of some vibrational modes or the convolution of vibrations and limited spectral resolution.     

Vibrational Energy—Spectra and Infraned Absorption of α—Helical Protein Molecules

The quantum energy spectran,including high excited states,of vibrational amide-I or of intramolecular excitations in α-helical protein molecules,are calculated by the discrete nonlinear Schrodinger equation together with the parameters appropriate to the systems.The distribution of energy levels obtained is basically consistent with the experimental values obtained by infrared absorption and Raman scattering.Utilizing the energy spectra we explain the laser Raman spectrum from metabolically active escherichia coli and we present some further features of the infrared absorption of the protein molecules.     

Temperature—Dependent Raman Spectra and Microstructure of Barium Metaborate Crystals and Its Melts

We have measured the Raman spectra of β-and α－barium metaborate in crystal and liquid states from room temperature to 1873K,with a semiconductor laser as the laser source,coupled with a time-resolved detection system to eliminate the dense thermal emission background when temperature was considerably high.Temperature-dependent Raman spectra can clearly indicate that the phase transformation from β-to α-barium metaborate has been completed during 1273-1300K.Variations of different kinds of microstructure units with temperature are identified and discussed.     

An Ab-Initio Calculation of Raman Spectra of Binary Sodium Silicates

Raman spectra of binary sodium silicates are calculated by self-consistent field (SCF) molecular orbital ab initio calculation of the quantum chemical method with several poly silicon-oxygen tetrahedral model clusters when both the basis sets of 6-31 G and 6-31 G(d) are applied. The symmetric stretching vibrational frequency of     

Photometric and fluorimetric study of the acid-base behavior of 2,2′-diquinolyl and 2,2′,2″-terpyridyl

A photometric and fluorimetric study of the acid-base behavior of 2,2-diquinolyl and 2,2,2-terpyridyl was performed. In sulfuric acid medium, the doubly charged 2,2-diquinolynium ion undergoes the first dissociation atH ₀=0.20±0.09, as determined by fluorimetry (_ex=336 nm, _em=424 nm). Photometric titration is less accurate because of the overlapping of the absorption spectra. The second dissociation constant of 2,2-diquinolyl was determined by fluorimetric titration (_ex=336 nm, _em=420 nm), obtaining a value of 3.67±0.03. The triply charged 2,2,2-terpyridyl molecule was found to undergo the first dissociation atH ₀=–7.17±0.04, as determined by fluorimetric titration (_ex=316 nm, _em=350 nm), in aqueous sulfuric acid medium. Photometric titration (=335 nm) was performed in the presence of 6.5% ethanol because of the low solubility of the compound in water. In this ethanolicwater medium, a value of the dissociation constant atH ₀=–7.39±0.03 was calculated. The second dissociation constant was determined to be 2.81±0.12 by photometric titration at 285 nm, and values of 4.03±0.26 and 4.16±0.20 were found for the third dissociation constant by photometric titrations at 320 and 295 nm, in 10% ethanol, in close agreement with previously reported values. The fluorimetric titration profile obtained by exciting at 274 nm and measuring the fluorescence emission at 350 nm, in the zone betweenH ₀=–3 and pH=10, is complicated by the several equilibria involved.