Fourier transform Raman and infrared and surface-enhanced Raman spectra for rhodamine 6G

The vibrational spectra of rhodamine 6G (R6G) are discussed on the basis of Fourier transform infrared and Fourier transform Raman spectra obtained far from resonance which are compared with resonance Raman and surface-enhanced resonance Raman spectra obtained with excitation at 457.9 nm. The behaviour of several bands is described and tentative assignments are proposed. Stong resonance Raman effects are observed for bands assignable to xanthene ring stretching modes and also xanthene ring deformation modes. Some of these are sensitive to the complexing of R6G with silver colloids.     

Structural analysis and Fourier transform infrared and Raman spectra of dibutoxyphosphoryl benzylisothiourea

A structural analysis for dibutoxyphosphoryl benzylisothiourea (DBBT) was carried out by mass spectrometry, 1H NMR, 13C NMR, infrared and Raman spectroscopy. The Fourier transform infrared and Fourier transform Raman spectra of liquid of DBBT were carried out with the purpose of studying the tautomerism (structures I and II) and the behavior of the more polar absorption's bands in different solvents, i.e., absorption's of the P=O and C=N bands. The results suggest the existence of tautomerism in the pure (liquid) compound and in solution of CHCl(3), CH(2)Cl(2), CHBr(3), and THF, C(2)H(4)Cl(2) and C(2)H(4)Br(2). The solvent interaction with the P=O band was characterized by the presence of a new band in the region of the O-H absorption. A vibrational assignment of the IR bands and Raman shifts was done and is proposed in this paper.     

Density functional theory study of the Fourier transform infrared and Raman spectra of Cu(II) bis-acetylacetone

Fourier transform infrared and Fourier transform Raman spectra of Cu(II) bis-acetylacetone have been obtained. The geometry, frequency and intensity of the vibrational bands of this compound and its 1,5-(13)C(2), 3-(13)C, 1,3,5-(13)C(3), 2,4-(13)C(2), (18)O(2) and 2,4-(13)C(2)-(18)O(2) derivatives were obtained by the density functional theory (DFT) with the B3LYP functional and using the 6-31G(*) and 3-21G(*) basis sets. The calculated frequencies are compared with the solid infrared and Raman spectra. All the measured infrared and Raman bands were interpreted in terms of the calculated vibrational modes. The percentage of deviation of the bond lengths and bond angles gives a good picture of the normal modes, and serves as a basis for the assignment of the wavenumbers. Most computed bands are predicted to be at higher wavenumbers than the experimental bands. The calculated geometrical parameters show slight differences compared with the experimental results. These differences can be explained by the different physical state of Cu(II) bis-acetylacetone. The DFT-B3LYP calculations assumed a free molecule in the gas phase. Analysis of the vibrational spectra indicates a strong coupling between the chelated ring modes.     

Fourier transform infrared emission spectra of MgH and MgD

High resolution Fourier transform infrared emission spectra of MgH and MgD have been recorded. The molecules were generated in an emission source that combines an electrical discharge with a high temperature furnace. Several vibration-rotation bands were observed for all six isotopomers in the X (2)Sigma(+) ground electronic state: v=1-->0 to 4-->3 for (24)MgH, v=1-->0 to 3-->2 for (25)MgH and (26)MgH, v=1-->0 to 5-->4 for (24)MgD, v=1-->0 to 4-->3 for (25)MgD and (26)MgD. The new data were combined with the previous ground state data, obtained from diode laser vibration-rotation measurements and pure rotation spectra, and spectroscopic constants were determined for the v=0 to 4 levels of (24)MgH and the v=0 to 5 levels of (24)MgD. In addition, Dunham constants and Born-Oppenheimer breakdown correction parameters were obtained in a combined fit of the six isotopomers. The equilibrium vibrational constants (omega(e)) for (24)MgH and (24)MgD were found to be 1492.776(7) cm(-1) and 1077.298(5) cm(-1), respectively, while the equilibrium rotational constants (B(e)) are 5.825 523(8) cm(-1) and 3.034 344(4) cm(-1). The associated equilibrium bond distances (r(e)) were determined to be 1.729 721(1) A for (24)MgH and 1.729 157(1) A for (24)MgD.     

Fourier transform Raman and IR spectra of snake skin

The Fourier transform (FT) Raman and IR spectra of the shed dorsal skin of the snake Elaphe obsoleta (American black rat snake) are reported. Vibrational spectroscopic assignments are proposed for the first time. Although good quality Raman spectra were obtained from the hinge regions using an FT Raman microscope, the dorsal scale regions fluoresced even with 1064 nm IR excitation. This was ascribed to pigmentation markings on the scales.     

Fourier transform Raman and infrared spectra and normal coordinate analysis of organo-arsenic(III), -antimony(III) and -bismuth(III) thiolates

The FT-Raman and infrared spectra of (PhS)BiPh2, (PhS)2BiPh, (PhS)3Sb, (PhS)3Sb, (PhS)3As and (PhSe)BiPh2 were measured in the range 3600-100 cm(-1). A normal coordinate analysis was performed for all substances in terms of the calculation and discussion of the force constants which are dependent on the element-sulphur and element-selenium group using a modified valence force field. Furthermore, for all compounds 1H-NMR, 13C-NMR and MS data were also given. The investigation of the microbiological activity of some substances against Escherichia coli was an additional aspect because of their strong bactericidal and fungicidal effects.     

Fourier transform infrared and Raman spectra, vibrational assignment and density functional theory calculations of naphthazarin

FT Raman and FTIR spectra of Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) and its deuterated analogue are recorded. Comparison between the spectra obtained by two techniques, a series of density functional theory (DFT) calculations and the spectral behavior upon deuteration were used for the assignment of the vibrational spectra of this compound. The calculated vibrational frequencies by the B3LYP, B3PW91, G96LYP, G96P86, and MPWLYP density functionals are generally consistent with the observed spectra. Infrared and Raman vibrational transitions predicted by B3LYP/6-311++G** are reported for the titled compound and its deuterated analogous and the assignments are discussed. All experimental and theoretical results support a relatively weak hydrogen bond in naphthazarin (NZ), compared with that in the enol form of normal beta-diketones. The observed nuOH/nuOD and gammaOH/gammaOD appear at about 3060/2220 and 790/560 cm(-1), respectively, which are consistent with the calculated hydrogen bond geometry and proton chemical shift results. Two bands at about 350 and 290 cm(-1) are assigned to the O...O stretching modes belong to A1 and B2 species, respectively.     

The Fourier Transform Raman and infrared spectra of naphthazarin

The FT Raman spectra of the three naphthazarin polymorphs have been recorded for the first time and compared with the FTIR spectra of the polymorphs and of naphthazarin with deuterated hydroxyl groups. It is possible to distinguish between the polymorphs, to deduce that the room temperature static symmetry point group of naphthazarin is C_2v, to assign the ν(CH), σ(OH), γ(OH) vibrations and to confirm the absence of the ν(OH) mode.     

Fourier transform infrared and Raman spectral investigations of 5-aminoindole

Fourier transform infrared (FT-IR) and Raman (FT-Raman) spectra of 5-aminoindole has been recorded and analysed. The FT-IR spectrum of the compound was recorded in a BrukerIFS 66 V spectrometer in the range 4000-400 cm(-1) and the FT-Raman spectrum was also recorded in the same instrument in the region 3500-100 cm(-1). Observed frequencies for normal modes are compared with those calculated form normal co-ordinate analysis. The shift in the frequencies of the fundamental modes with the substituent amino group and the mixing of different normal modes are discussed with the help of potential energy distribution (PED) calculated through normal co-ordinate analysis.     

Density functional theory study of Fourier transform infrared and Raman spectra of 2-amino-5-chloro benzonitrile

The vibrational spectra of 2-amino-5-chloro benzonitrile (ACB) have been obtained by density functional theory (DFT) calculations. Normal coordinate analysis has been carried out to support the vibrational analysis. The results were compared with the experimental values. With the help of scaling procedures, the observed FTIR and FT Raman vibrational frequencies were analysed and compared with the theoretically predicted vibrational spectra. The assignments of bands to various normal modes of the molecules were also carried out.     

Fourier transform infrared and Raman spectra, and AB initio calculations for cadmium(II)-cysteinate glycinate complex [Cd(Cys)(Gly)

The cysteinate glycinate cadmium(II) complex was synthesized and structural analysis was carried out using the following methods: determination of the C, H, N, S and O contents, thermogravimetry, infrared and Raman spectra. The most probable structure for the complex at a minimum of energy was calculated by the density functional theory (DFT):B3LYP/3-21G quantum mechanical method. The infrared and Raman spectra were analyzed and bands assigned through the DFT procedures, the stabilization energy being equal to: E(RB+HF-LYP)= -6442.67784a.u. Features of the infrared and Raman spectra confirm theoretical structural prediction with respect to the metal-ligand bonds: Cd-O, Cd-S and Cd-N. Full assignment of the vibrational spectra was also supported by a carefully analysis of the distorted geometries generated by the normal modes.     

Attenuated total reflection Fourier transform infrared spectra of faceted diamonds

In this work, the contributions of cationic and elemental gold on roughened gold substrates to surface-enhanced Raman scattering (SERS) of polypyrrole (PPy) films were first investigated. First, a gold substrate was roughened by a triangular wave oxidation-reduction cycle (ORC) in an aqueous solution containing 0.1 M KCl. Then, the roughened gold substrate was further reduced by applying a cathodic potential for a fixed time to control the quantity of unreduced cationic Au on the roughened Au substrate. The result indicates that the content of cationic Au is responsible for the improved SERS of PPy electrodeposited on this roughened Au substrate. This phenomenon can be attributed to the interfacial charge transfer from PPy to the roughened Au substrate by the aid of cationic Au.     

Low-temperature Fourier transform infrared spectra and hydrogen bonding in polycrystalline L-alanine

The 400-4000 cm(-1) FTIR spectra of pure NH and isotopically substituted (10 and 90% doped ND/NH) polycrystalline L-alanine were recorded in the temperature range 10-300 K. The observed temperature dependence and isotopic shifts behavior enabled to identify, in the spectra of the doped crystals, three well-separated bands ascribable to either the NH or ND stretching vibrations associated with the three different types of hydrogen bonds existing in the crystal. The observed red shifts of these bands relative to the frequency of a reference "free" NH (or ND) stretching mode were found to correlate well with the H-bond distances found in the crystal and provide an indirect way of estimating the enthalpies associated with each type of H-bond found in the crystal. In the low-frequency deformation and torsional spectral region (below 2000 cm(-1)), several bands, which were found to be affected by isotopic substitution, were identified as belonging to the NH3(+) group. Several bands show splitting at low temperatures, indicating the occurrence of a significant reorganization in the crystal structure, which with all probability results mainly from changes in the proton positions. Finally, the literature assignments of the IR spectra of both crystalline NH3(+) and ND3(+) L-alanine were revised taking into consideration their temperature dependence and behavior upon deuteration.     

Synthesis, Fourier transform infrared and Raman spectra, assignments and analysis of N-(phenyl)- and N-(chloro substituted phenyl)-2,2-dichloroacetamides

N-(phenyl)-2,2-dichloroacetamide (NPA) and N-(chloro substituted phenyl)-2,2-dichloroacetamides of the configuration XyC6H(5-y)-NHCO-CHCl2 (where, X = Cl and y = 1, 2 and 3) were synthesised and the Fourier transform infrared (FTIR) and Fourier transform Raman (FT-Raman) spectra of the compounds were recorded and analysed. The FTIR spectra of all the compounds were recorded in a Bruker IFS 66V spectrometer in the range of 4000-400 cm(-1) and the FT-Raman spectra were also recorded in the same instrument in the region 3500-100 cm(-1). The variation of an amide bond (-NHCO-) parameters with the substitution of the chlorine atom in the phenyl group and the mixing of different normal modes are discussed with the help of potential energy distribution (PED) calculated through normal co-ordinate analysis.     

Fourier transform infrared and Raman spectral analysis of trans-1,4-polyisoprene.

Polyisoprene is the most widely used polymer in industry and commerce. Fourier transform infrared (FTIR) and Raman spectra of trans-1,4-polyisoprene have been recorded in the range of 4000-400 and 4000-100 cm(-1), respectively. In the present investigation, detailed assignments of the observed fundamental bands of trans-1,4-polyisoprene has been analysed in terms of peak positions and relative intensities. With the hope of providing more and effective information on the fundamental vibrations, a normal co-ordinate analysis has been performed on trans-1,4polyisoprene, by assuming Cs symmetry. The simple general valance force field (SGVFF) method has been employed in normal co-ordinate analysis and to calculate the potential energy distribution (PED) for each fundamental vibration. The PED contribution corresponding to each of the observed frequencies shows the reliability and accuracy of the spectral analysis. The validity of the SGVFF method as a practical tool for complete analysis of vibrational spectra, even for a polymer of this complexity, is confirmed in the present work.     

Combined Fourier transform infrared and Raman spectroscopic studies of some carbonyl-diphosphine-indenyl-iron cations

The Fourier transform infrared and Raman spectra of the cations [η⁵-C₉H₇Fe(CO)_n dppa]⁺ (n = 1, 2; dppa=bisdiphenylphosphinoalkane, where alkane=methane, ethane, butane, hexane and octane) and [{η⁵-C₉H₇Fe(CO)₂}₂-μ-dppa]²⁺ indicate that the alkyl chain lengths have effects on the structures of the bidentate cations resulting in increased back-donation to carbonyl groups as the chain length increases. In contrast the alkyl chain lengths have no similar effects in the unidentate mononuclear and bridged cations.     

Comparative analysis of smokeless gunpowders by Fourier transform infrared and Raman spectroscopy

Fourier Transform Infrared (FTIR) and Raman spectroscopic techniques were used to perform a comparative study of the spectral profiles of single-base, double-base and triple-base smokeless gunpowders. Preliminary results based on visual comparison of the spectra point out that spectra obtained by both vibrational techniques were useful for a rapid identification of gunpowders containing dinitrotoluene as one of the major components and triple-base gunpowders. Additionally, the Raman spectra of gunpowders with diphenylamine in its primary composition showed a characteristic band, assigned to 2-nitro-diphenylamine, allowing the identification of this type of gunpowders.     

A preliminary study of the Fourier transform Raman spectra of polystyrenes

The Fourier transform Raman spectra of several isotactic and atactic polystyrene samples are presented. Correlations between the spectra and the crystallinity and conformation of the samples are discussed.     

A standardised intensity scale for Fourier transform Raman spectra of liquids

A method is proposed for producing a standardised intensity scale for liquid spectra measured on Fourier transform Raman spectrometers. The method uses hexachlorobutadiene as an external standard, and relies upon the high degree of reproducibility available between spectra on a Fourier transform Raman instrument. This procedure is designed primarily to be simple to use and easy to automate in order that it may be applied in routine analytical laboratories with a minimum of recording and processing time. Limitations to the technique and alternative means of standardisation are discussed.