bluuebunny/crossref_metadata_2025 huggingface dataset:
Remote sampling using a fibre‐optic probe in fourier transform Raman spectroscopy
Authors: Williams K. P. J.
Published: May 2005

Fourier transform Raman spectroscopy has been carried out remote from the instrumentation using fibre‐optic probes. The quality of the data is good; the measured signal‐to‐noise ratios from spectra obtained using a conventional sampling arrangement are better only by a factor of ca. 5. The choice of fibre‐optic material and grade is crucial to the success of this work. Two different fibres have been tested and compared. Technical improvements are discussed.
Raman scattering investigation of lead mixed halides, PbCl2xBr2(1 − x), as a function of the proportion × ϵ [0, 1]
Authors: Carabatos‐Nédelec C. , Lumbreras M.
Published: May 2005

PbCl2xBr2(1 − x) single crystals for various compositions were studied by Raman spectroscopy at 14 K. It is shown that the phonons are of one‐ or two‐mode behaviour when the proportion x varies from 0 to 1. Lattice dynamic and group theory considerations related to structural data allow one to establish a mechanism for the substitutional filling of the anion sites and their participation in the lattice vibrations, the frequency of which has been measured as a function of x at 14 K. The maximum disorder given by the Raman line widths occurs for x = 0.25 and x = 0.75, in accordance with dielectric measurements.
Molecular distortion of distamycin on binding to DNA as revealed by Raman spectroscopy
Authors: Lu Dong Sheng , Nonaka Yasuomi , Tsuboi Masamichi , Nakamoto Kazuo
Published: May 2005

The Raman spectra of distamycin and its complex with DNA were examined in both H2O and D2O solutions. To facilitate band assignments, Raman spectra of several small model compounds of distamycin were also obtained. On binding to DNA, the CO stretching band at 1620 cm−1 (amide I band) of distamycin was shifted upwards by 14 cm−1, whereas a strong pyrrole‐ring stretching band at 1437 cm−1 was shifted downwards by 7 cm−1 in H2O. In addition, most of the Raman bands including amide I, II and III became narrower and sharper on binding to DNA. These results indicate that, in the free state, the dihedral angles around the CC and NC bonds connecting the pyrrole ring and the peptide chain of distamycin fluctuate near 0° (coplanar configruation), whereas in the bound state these angles are fixed and markedly shifted from 0°. Previous x‐ray and NMR studies on distamycin (netropsin)–DNA complexes show that such deviations occur when these drug molecules are bound in the minor groove of DNA. Molecular distortion of distamycin caused by interaction with other polynucleotides has also been elucidated by using such spectral characteristics as diagnosis.
Effective dielectric constants and electromagnetic enhancement on metal island films
Authors: Martín F. , de Saja J. A. , Aroca R.
Published: May 2005

An effective dielectric constant for metal island films has been evaluated using a parametrization of the optical property in terms of the packing factor, the film thickness and a distribution of axial ratios for spheroidal particles. Electron micrographs and plasmon absorption spectra of discontinuous films served as references for parametrical fitting. Enhanced Raman intensities of molecules oriented on the surface of oblate spheroids and a backscattering geometry are discussed.
Vibrational Raman optical activity in forward scattering: Trans‐pinane and β‐pinene
Authors: Barron L. D. , Hecht L. , Gargaro A. R. , Hug W.
Published: May 2005

The first measurements of vibrational Raman optical activity (ROA) have been performed employing a forward scattering geometry. Forward‐scattered ROA spectra of (+)‐trans‐pinane and (−)‐β‐pinene are presented as first examples. Comparison with the corresponding backward‐and right‐angle‐scattered spectra confirmed that the bond polarizability theory of ROA is a good approximation for trans‐pinane, and has identified unequivocally a large isotropic contribution to the ROA in β‐pinene bands at 716 and 765 cm−1 ascribed to interactions between the olefinic methylene twist and a skeletal mode of the pinane structure. Unless large isotropic contributions are present, which is unusual, forward scattering is by far the least favourable of the ROA measurement strategies, which might explain the failure of recent attempts to observe ROA in coherent anti‐Stokes Raman scattering.
Hyper‐Raman spectroscopy
Authors: Ziegler L. D.
Published: May 2005

Recent experimental and theoretical developments in spontaneous hyper‐Raman spectroscopy (HRS) are reported. The scope of the general review of HRS presented summarizes the results of this non‐linear scattering technique during the past 10 years. In particular, those aspects of HRS studies which allow novel observations as compared with other spectroscopic techniques are emphasized. HRS investigations of crystals, liquids and surface and electronic resonance enhancement are highlighted.
Symmetric and non‐symmetric hyper‐Raman scattering: Its polarization states and angular dependences
Authors: Kielich Stanisław , Bancewicz Tadeusz
Published: May 2005

A theory of three‐photon (hyper‐Raman and hyper‐Rayleigh) scattering is proposed using the approach of irreducible Cartesian and spherical tensors. A general expression for the intensity‐time correlation function of symmetric, non‐symmetric and symmetric‐non‐symmetric three‐photon scattering is derived in terms of separated, irreducible field‐and molecular‐rotational invariants. The occurrence of the various types of scattering is dependent on the physical conditions, i.e. on the molecular symmetry and the ratio of the light frequency and molecular frequency. The (general) number of five irreducible molecular‐rotation and field invariants can undergo a reduction under appropriately chosen experimental and model conditions. The expressions for the intensity function hold for arbitrary (e.g. elliptical) states of light Polarization and angulardistributions. In particular, they are applied to linear and circular polarization. On their basis, equations are derived for the depolarization ratio and reversal coefficient of hyper‐Raman and hyper‐Rayleigh scattering.
Surface‐enhanced hyper‐Raman spectroscopy with a picosecond laser. New vibrational information for non‐centrosymmetric carbocyanine molecules adsorbed on colloidal silver
Authors: Yu Nai‐Teng , Nie Shuming , Lipscomb Leigh Ann
Published: May 2005

Picosecond‐excited surface‐enhanced hyper‐Raman scattering (SEHRS) spectra have been obtained for several non‐centrosymmetric oxa‐ and thia‐carbocyanine molecules adsorbed on pre‐aggregated colloidal silver. To facilitate interpretation of the SEHRS results, a comprehensive vibrational study of these dyes by employing Fourier transform (FT) IR spectroscopy, surface‐enhanced Raman scattering (SERS) and the newly developed techniques of near‐IR‐excited FT‐Raman and FTSERS is also reported. The SERS spectra of these carbocyanine dyes are dramatically different from their bulk FT‐Raman and SERS spectra, but exhibit similarities to their FTIR spectra. Many SEHRS lines appear to arise from vibrational modes of the central π‐conjugated chain, in contrast to the appearance of predominantly end‐chromophore vibrations in the Raman spectra. Some of the intense surface hyper‐Raman lines are found to be experimentally undetected or unresolvable by Raman scattering and IR absorption. The results thus conclusively demonstrate that, for non‐centrosymmetric molecules, surface‐enhanced hyper‐Raman scattering is capable of providing important vibrational information that is unobtainable through the Raman and IR methods.
Raman investigation of simple and complex oxides of platinum
Authors: Graham G. W. , Weber W. H. , McBride J. R. , Peters C. R.
Published: May 2005

Raman spectra were obtained from PtO, Pt5O6, Pt3O4, α‐PtO2, β‐PtO2, MxNayPt3O4 (M = Co, Ni), PtCoO2 and MPt3O6 (M = Mn, Co, Cd). An enumeration of the allowed Raman modes is made for all of these oxides except Pt5O6, for which the structure is unknown. Polarization measurements allow symmetry species assignments to be made for the lines from α‐PtO2 and PtCoO2, and a likely assignment of the lines from β‐PtO2 is made by analogy with rutile‐structured materials with the rutile structure.
Etude Spectrale de l'Acide Glycolique, des Glycolates et du Processue de Polymérisation
Authors: Cassanas G. , Morssli M. , Fabrègue E. , Bardet L.
Published: May 2005

Les spectres Raman et infrarouges de l'acide glycolique, de l'ion glycolate et du glycolate de méthyle ont été analysés de 200 à 4000 cm−1. l'acide glycolique et l'ion glycolate en solution aqueuse se présentent sous forme de monomères hydratés admettant un plan de symétrie, tandis que le glycolate de méthyle possède deux formes d'association, l'une avec une liaison H‐intramoléculaire, l'autre avec une liaison H‐intermoléculaire entre groupements hydroxyles. La déshydratation progressive à température élevée de la solution d'acide glycolique a permis d'identifier les bandes caractéristiques de l'estérification, mettant en évidence le début de la polymérisation.
Resonance Raman spectra of cytochrome a in cytochrome oxidase: Excitation in the 605‐nm absorption region
Authors: Centeno J. A. , Babcock G. T.
Published: May 2005

Visible excitation resonance Raman difference spectra, in resonance with the 605‐nm absorption maximum of fully reduced and mixed‐valence cyanide‐bound cytochrome oxidase, were recorded. Under these conditions, the vibrations of ferrocytochrome a are markedly enhanced owing to its dominant contribution to the 605‐nm α‐band absorption of reduced cytochrome oxidase. The effect of H/D exchange in the Raman spectra of cytochrome a was also investigated as a way to establish formyl‐ and vinyl‐peripheral substituent sensitive modes. Measurements of the depolarization ratio dependence of cytochrome a vibrational modes resulted in some isotope‐sensitive modes with characteristic depolarized behavior; however, it was observed that the majority of the visible excitation vibrations exhibit polarized values. This is interpreted as being due to a significant lowering in the molecular symmetry of the heme a porphyrin macrocycle caused by the unusual peripheral substituent pattern of heme a and, presumably, by the strong cytochrome a‐protein interactions. Both structural effects appear to result in a selective enhancement of cytochrome a Eu substituent‐sensitive modes as detected by the low‐frequency resonance Raman spectrum.
Raman microspectrometric study of the dissolution layer of M(NO3)2·nH2O crystals (M = Mg, Ca, Zn and Cd) in their undersaturated aqueous solutions
Authors: Koussinsa Félix , Bertin François
Published: May 2005

The composition of the dissolution layer of certain divalent metal nitrates crystals such as Mg(NO3)2, Ca(NO3)2, Zn(NO3)2 and Cd(NO3)2 in their respective undersaturated solutions was studied by Raman microspectrometry using multi‐channel acquisition of data. A preliminary examination of homogeneous saturated and 20% undersaturated solutions of every solute considered confirmed the existence of individual Raman bands which could be assigned to different solvated species, namely free aquated ions, solvent‐separated ion pairs and contact ion pairs. Some spectral differences were noted between the four cations involved. With Ca2+, Zn2+ and Cd2+ a weak band, assigned to ion aggregates, was also identified. Micro‐Raman spectra of dissolution layers recorded at several steps of the crystal dissolution showed a considerable increase in the proportions of aggregates or contact ion pairs, depending on the type of solute examined. Sharp differences between the dissolution layer composition for Group IA, IIA and IIB metal nitrates were observed.
Theoretical analysis of the resonance Raman spectrum of tryptophan
Authors: Marconi Giancarlo
Published: May 2005

The resonance Raman excitation profiles of tryptophan in the region 240‐200 nm were calculated, taking into account the molecular properties of its chromophore, indole. The relevant quantities such as state displacements and vibronic coupling terms were evaluated by means of quantum mechanical semi‐empirical methods. The results allow the identification of the strongest modes and of the main mechanism governing the Raman scattering. It is found that the spectrum is dominated by the terms in resonance with the Bb and Ba states of indole, with possible interference between these contributions. The vibronic effects, negligible in resonance, become important in preresonance regions.
Vibrational spectra of lactic acid and lactates
Authors: Cassanas G. , Morssli M. , Fabrègue E. , Bardet L.
Published: May 2005

The Raman and IR spectra of lactic acid and sodium lactate in aqueous solution and methyl lactate as a pure liquid were recorded from 3600 to 100 cm−1. Vibrational assignments are proposed for the three compounds. The effects of hydrogen bonding on the ΔOH vibrations of the hydroxyl alcohol group were studied and the results suggest both inter‐ and intra‐molecular hydrogen‐bonded association.
Vibrational spectra of α‐CaNa2P2O7 · 4H2O, CaNH4NaP2O7 · 3H2O and CdNH4NaP2O7 · 3H2O
Authors: Joe I. Hubert , Aruldhas G. , Keresztury Gabor
Published: May 2005

The IR and Raman spectra of polycrystalline samples of α‐CaNa2P2O7 · 4H2O, CaNH4NaP2O7 · 3H2O and CdNH4NaP2O7 · 3H2O were recorded and analysed. Vibrational bands due to NH4+, P2O74− and H2O are identified. The POP bridge angle is found to be about 129° and the pyrophosphate ion is non‐centrosymmetric. The NH4+ ion is likely to be rotating freely in the componds XNH4NaP2O7 · 3H2O (X = Ca, Cd).
Effect of correlation between electronic and vibrational dephasing processes on Raman band shapes
Authors: Torii Hajime , Tasumi Mitsuo
Published: May 2005

A theory for Raman band shapes is developed by using the stochastic model. The correlation between electronic and vibrational dephasing is taken into account explicitly. Raman bands become significantly asymmetric in the case of a strong correlation. The Raman band shape can therefore be used to estimate the extent of correlation between the electronic and vibrational dephasing processes. The fact that Raman bands are usually Lorentzian means that the two dephasing processes are not strongly correlated in many cases. The microscopic aspect of the dephasing processes is discussed.
Chemical effect of chloride ions on SERS in silver sol
Authors: Fu Shi‐You , Zhang Peng‐Xiang
Published: May 2005

The influence of chloride ions on surface enhanced Raman scattering (SERS) and the time dependence of the SERS intensity of p‐aminobenzoic acid (PABA) and pyridine in silver sol were studied. The addition of chloride ions can destroy the equilibrium between the gas‐like and the solid‐like phase adsorption of PABA on the silver surface and causes a transformation of the molecular adsorption state and a reduction in the SERS intensity. The influence of chloride ions on SERS and the time dependence of SERS intensity in PABA—silver sol and pyridine—silver sol mixtures were studied. It was found that, in the same environment, the SERS' intensity of pyridine increases and that of PABA decreases on addition of KCl. The results show that the chemical effect of chloride ions on SERS of PABA and pyridine in silver sol is overwhelming. The results of light absorption of PABA and pyridine in silver sol are consistent with this conclusion.
Raman spectra of LnAl3Cl12 compounds
Authors: Shamir J. , Hake D. , Urland W.
Published: May 2005

The Raman spectra of three LnAl3Cl12 compounds (Ln = Gd, Tb and Dy) were studied and the observed bands are interpreted on the basis of terminal and bridging AlCl bonds and LnCl bonds. The results support the suggestion that the AlCl4 species are of anionic type in association with cationic Ln species.
Raman and infrared spectra, conformational stability, barriers to internal rotation, vibrational assignment and ab initio calculation of bromoacetone
Authors: Durig J. R. , Lin Jie , Phan H. V.
Published: May 2005

Raman (3200—10 cm−1) and infrared (3500—20 cm−1) spectra were recorded for gaseous and solid bromoacetone (1‐bromopropan‐2‐one), CH2BrC(O)CH3. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. These data were interpreted on the basis that the molecule exists predominantly in a gauche conformation of C1 symmetry (dih ∢ BrCCO = 111.8°) in the vapor. In the liquid a second conformer having a trans structure (bromine atom oriented trans to the methyl group) with Cs point group symmetry is also present, and the trans form is the only conformer present in the annealed solid. From a study of the Raman spectrum of the liquid with variable temperatures the trans conformer was determined to be more stable than the gauche form by 385 ± 61 cm−1 (1.09 ± 0.17 kcal mol−1). A complete vibrational assignment is proposed for both conformers. From ab initio Hartree‐Fock gradient calculations with the 4—31G*/MIDI‐4* basis set, optimized geometries for both the gauche and trans conformers were obtained. Similar calculations were also carried out for fluoroacetone and chloroacetone utilizing the 6—31G* basis set with electron correlation with secondorder perturbation. The conformational stabilities, barriers to internal rotation and observed fundamental vibrational frequencies for both the gauche and trans conformers of bromoacetone are compared with those calculated with the STO‐3G* basis set. The results are discussed and compared with the corresponding quantities obtained for some similar molecules.
Raman spectra of tetragonal lanthanide oxychlorides obtained from polycrystalline and single‐crystal samples
Authors: Del Cul G. D. , Nave S. E. , Begun G. M. , Peterson J. R.
Published: May 2005

The reported Raman spectra of the tetragonal [lead chlorofluoride‐type structure, D‐P4/nmm (ITC No. 129)] lanthanide oxychlorides are inconsistent. Nuclear site symmetry analysis predicts six Raman bands. Five peaks are consistently observed, whereas the sixth remains controversial. Also, two different sets of irreducible representations are reported:

which include the three acoustic modes, A2u{T z} and Eu{Tx, Ty}. The present analysis of the polarized Raman spectra from PrOCI and NdOCI single crystals clearly showed that the correct irreducible representation contains the B2g symmetry. The symmetries of three Raman‐active bands are well determined, a fourth band displays two polarizations and a fifth band has no clear polarization and is assigned Eg by default. The EuOCl Raman spectrum exhibits a weak electronic Raman band which originates in electron‐phonon coupling as a result of the closeness between the vibrational and electronic eigenvalues. The low‐energy band (LaOCl, 67 cm−1; EuOCI, 70 cm−1; and GdOCl, 65 cm−1) and the high‐energy band (525 cm−1 for LaOCl) reported by others for selected lanthanide oxychlorides were not observed in the present work.
Catalytic mechanism of cytochrome c oxidase
Authors: Rousseau Denis L. , Han Sanghwa , Song Sunho , Ching Yuan‐Chin
Published: May 2005

The structures and kinetic properties of intermediates in the reaction of cytochrome c oxidase with oxygen initiated by CO photolysis were elucidated by resonance Raman scattering studies. These studies led to a postulated model for the reaction involving an initial intermediate with properties similar to oxyhemoglobin, a peroxo intermediate, a ferryl intermediate and a hydroxy intermediate. The influence of initiating the reaction by CO photolysis was tested by comparing the resonance Raman spectra of the reaction product at 10 ms with that generated by directly mixing oxygen with the enzyme in the absence of CO. Different final products were found for these two protocols. It is proposed that in the absence of CO two molecules of O2 can bind simultaneously at the binuclear site. For single turnover conditions this prevents the reaction from going to completion. However, under physiological conditions where there is a continuous supply of electrons this second molecule of oxygen at the binuclear site places no restrictions on the catalytic mechanism. Instead, it assures an available supply of oxygen to the catalytic site. A model for the reaction under physiological conditions is postulated.
Raman and kinetic studies of myoglobin structure and dynamics
Authors: Champion P. M.
Published: May 2005

Resonance Raman spectroscopy is used to analyze the absorption line shapes of myoglobin (Mb), its CO ligated complex (MbCO) and the low‐temperature photoproduct (Mb*, CO). Energetically significant inhomogeneous broadening is detected in the line shapes of the unligated species and a strong coupling to low‐frequency (CO torsional) modes is found for MbCO. These observations lead naturally to a simple model of the protein–heme system and its thermally induced conformational fluctuations. The model is used to analyze the non‐exponential ligand binding, optical line shifts and kinetic holeburning exhibited by (Mb*, CO) at low temperatures. The model makes a specific prediction for the high‐temperature Arrhenius barrier at the heme that is found to be in good agreement with kinetic measurements as a function of temperature near 293 K. It is also found that the geminate phase of ligand rebinding remains non‐exponential even at these higher temperatures and it is shown that this is due to a homogeneous relaxation process (probably involving changes in the distal pocket protein conformation following photolysis) rather than to an inhomogeneous distribution of heme rebinding barriers. Slow distal pocket fluctuation time scales are also revealed by using a two‐pulse photolysis protocol to select kinetically a rapidly rebinding sub‐population of the ensemble. These experiments allow the direct monitoring of the time scales of the large‐scale distal pocket interconversions that average the ‘open’ (A0) and ‘closed’ (A1) states of myoglobin.
Fourier transform Raman spectra of diamond‐like carbon films
Authors: Durig J. R. , Little T. S. , Bist H. D. , Rengen A. , Narayan J.
Published: May 2005

Fourier transform (FT) Raman spectra (3500–50 cm−1) were recorded for hard diamond‐like carbon (DLC) films deposited on silicon wafer substrates at various temperatures. The observed frequency of the graphitic optic zone center phonon (G) at 1595 cm−1 was found to remain constant with variations in the deposition temperature of the substrate, the excitation wavelength and the laser power. However, the disorder activated optical zone edge phonon (D), observed in the 1380–1250 cm−1 region, exhibits changes in the band maximum frequency with the above‐mentioned variables. FT Raman spectroscopy, applied to these films, is shown to be a useful probe for the identification of various different types of diamond‐like structures which are present.
Absorption, resonance Raman and resonance CARS investigations on the permanganate ion doped in potassium perchlorate single crystals at low temperatures
Authors: Leuchs M. , Materny A. , Göttges D. , Schaschek K. , Kiefer W.
Published: May 2005

Solid‐state absorption, resonance Raman and resonance CARS spectroscopy were applied to investigate the vibronic properties of the permanganate ion doped in KClO4 single crystals. Experiments were performed for all three types of spectroscopy at 15 K. At this temperature the vibronic structure in the absorption spectrum is highly resolved, allowing detailed studies of resonance Raman and resonance CARS spectroscopy. Selected experimental results are presented.
Resonance Raman spectra of the S3 molecule in sulphur vapour
Authors: Picquenard E. , El Jaroudi O. , Corset J.
Published: May 2005

Sulphur vapour was investigated by Raman spectroscopy using six laser excitation wavelengths located in the electronic absorption band of the S3 molecule (406.7–514.5 nm). With excitation wavelengths close to the S3 λmax (395 nm) the spectra are mainly resonance enhanced. With the excitation located in the S3 electronic absorption band edge the observed resonance Raman spectra are mainly due to the vibrationally excited molecules. Most Raman lines involve transitions between overtone or combination levels of the symmetric stretching (ν1) and symmetric bending (ν2) modes. The comparison of spectra of samples with various 34S contents recorded with various excitation wavelengths enable us to determine the ω10 and ω20 harmonic wavenumbers and the anharmonicity constants x x and x, for 32S3 and 34S3. New assignments are proposed for all Raman lines observed. A valence force field treatment with the calculated geometry rss = 1.988 Å and α = 117° yields force constants ƒr = 3.91 mdyn Å−1 and ƒrr = 0.36 mdyn Å−1. These force constants are compared with those of the parent X2 or X3 molecules (X = O, S, Se or Te).
Analyse Vibrationnelle des Acides gem‐Dimethylglutarique en Solution Aqueuse II—Acide 3,3‐Dimethylglutarique et Ses Sels de Potassium
Authors: Yolou S. , Delarbre J. L. , Bourret E. , Roger J. , Maury L.
Published: May 2005

Les spectres Raman et infrarouges de l'acide 3,3‐diméthylglutarique et de ses sels de potassium en solution aqueuse (H2O et D2O) ont été enregistrés de 200 à 4000 cm−1. L'analyse de l'état de polarisation des raies Raman montre que l'acide 3,3‐diméthylglutarique et son sel neutre de potassium appartiennent au groupe de symétrie C2 tandis que le sel acide répond au groupe de symétrie Cs. Une attribution des vibrations fondamentales est proposée.
Surface‐enhanced Raman scattering of Ru(II) homo‐ and heterolytic complexes with 2,2′‐bipyridine and 1,1′‐biisoquinoline in aqueous silver sol
Authors: Zhu Zi‐Ying , Mao Chen , Yang Rui‐Yang , Dai Li‐Xin , Nie Chong‐Shi
Published: May 2005

SERS and SERRS spectra in aqueous silver sol for Ru(II) polypyridine complexes with 2,2′‐bipyridine (bpy) and 1,1′‐biisoquinoline (Q) [Ru(bpy), RuQ, Ru(bpy)2Q2+ and Ru(bpy)Q] were observed with 457.9, 488.0, 514.5 and 632.8 nm excitation. The vibrational modes of the conjugated ring system in the 1600–1400 cm−1 region are enhanced by the resonance effect. Some bands in the SERS spectra of the four complexes show remarkably high intensities with longer wavelength excitation. This may be explained by surface selection rules.
Fourier transform Raman spectroscopy of brightly colored commercially available dyestuffs and pigments
Authors: Durig J. R. , Zunic W. M. , Costner T. G. , Guirgis G. A.
Published: May 2005

Fourier transform (FT) Raman spectroscopy is shown to be a very powerful and valuable technique for the analysis of brightly colored dyestuffs and pigments. The use of a near‐infrared Nd: YAG laser, as opposed to visible lasers used in conventional Raman instrumentation, virtually eliminates fluorescence from the dye, thus allowing high‐quality Raman spectra to be collected. The small amount of sample required and the limited sample preparation involved also make FT Raman spectroscopy attractive when the amount of sample available is limited or when a rapid, reliable analysis is needed. FT Raman spectra along with the complementary FT‐IR spectra of various commercially available dyestuffs and pigments are presented.
Raman scattering study of [N(CD3)4]2ZnCl4 under hydrostatic pressure
Authors: Henocque J. , Hedoux A. , Sauvajol J. L.
Published: May 2005

Raman spectra were measured for [N(CD3)4]2ZnCl4 over the pressure range 1–2000 bar. The influence of pressure was studied for the ZnCl4 bending modes and the 24 cm−1 phonon peak. The pressure dependence of these modes was interpreted having regard to the phase transitions predicted by the temperature–pressure diagram. The pressure dependence of all the recorded spectra highlights a critical behaviour at about 500 bar which does not correspond to any phase transition in the diagram. This phenomenon was interpreted by consideration of the modulation characteristics.
Micro‐Raman analysis of thin‐film diamond temperature sensors
Authors: Bhargava S. , Joshi H. , Bist H. D. , Aslam M.
Published: May 2005

Thin‐film diamond temperature sensor arrays used in harsh aerospace environments were investigated using micro‐Raman spectroscopy. Raman spectra of three of the samples obtained under specific experimental conditions are presented. On annealing a sample, an increase in graphite content and restoration of long‐range order in its lattice are suggested. Additionally, an untreated sample on irradiation with 1064 nm radiation from a low‐power continuous‐wave Nd: YAG laser exhibits an increase in graphite content. Similar irradiation of an annealed sample shows an increase in the graphite content, a decrease in diamond‐like carbon content and the appearance of a band at 1607 cm−1.
Vibrational Raman spectroscopy of polyconjugated organic oligomers and polymers
Authors: Castiglioni C. , Del Zoppo M. , Zerbi G.
Published: May 2005

New classes of polymers and oligomers whose backbone consists of a network of delocalized π electrons have recently been synthesized and show electrical and non‐linear optical properties of great interest for new technologies. The vibrational spectra of these materials show peculiar features which, if properly interpreted, can provide unique structural information. The interpretation of the spectra requires the development of new theoretical tools. The theoretical and experimental aspects of the problem are presented. It is also shown that the nuclear relaxation following the excitation of the electrons by an intense electromagnetic field can be described in terms of the vibrational modes and can be related to the nuclear contributions to the non‐linear optical responses of the material. In this case Raman intensities play a determining role.
Raman study of aqueous HX solutions (X = F, Cl, Br and I) in both liquid and glassy states
Authors: Kanno H.
Published: May 2005

Raman spectra of aqueous HX solutions (X = F, Cl, Br and I) were measured in botl: the liquid and glassy states. It is shown that the preresonance Raman effect is the major factor for the intensity increase in the Raman spectra with increase in halide concentration. The general spectral features are essentially the same as those for aqueous LiX solutions when the contributions of oxonium ions are excluded. The Raman bands of oxonium ions were observed better in the Raman spectra of glassy HX solutions.
SER spectra of acridine and acridinium ions in colloidal silver sols. Electrolytes and PH effects
Authors: Lévi G. , Pantigny J. , Marsault J. P. , Aubard J.
Published: May 2005

Extensive surface‐enhanced Raman (SER) spectra of acridine and acridinium ions, taken as probes of DNA intercalating agents, were investigated in colloidal silver sols. From comparison of the SER and Fourier transform near‐IR Raman spectra, it is confirmed that acridine is adsorbed on the metal surface via its protonatable nitrogen atom with its plane perpendicular to the surface. The effects of the electrolyte composition of silver sols, the laser excitation wavelengths and the solution pH were carefully investigated. When present in the solution, halide ions increase the SER signal intensity and shift the nitrogen protonation towards high pH values. Moreover, SER spectra of acridinium (AH+) show a higher signal‐to‐noise ratio than those of the neutral species and this is particularly pronounced when halides ions are present in the silver sols. The additional enhancement probably originates from a resonant charge transfer which appears to be more efficient when AH+ species forms an ion pair with halide ions. The pKa of acridine on a silver surface was estimated from titration curves based on the intensity ratios of lines at ca. 1564 and ca. 1584 cm−1, characteristic of the neutral and the protonated species, respectively. The titration curves behave quadratically or linearly according to whether the silver sols do or do not contain halide ions. On the basis of the phenomenological electrochemical model, the pH was found to change more slowly in the double layer than in the bulk solution.
Raman confocal microprobing, imaging and fibre‐optic remote sensing: A further step in molecular analysis
Authors: Barbillat J. , Dhamelincourt P. , Delhaye M. , Da Silva E.
Published: May 2005

This paper reviews some recent developments in Raman instrumentation. The introduction of the confocal design in most Raman spectrometers represents the latest advance in the field of instruments for Raman spectroscopy. It is the basis of new applications in the field of Raman microprobing and improvements in Raman imaging techniques. The basic principle of confocal microscopy is reviewed and its extension to Raman spectroscopy is discussed in terms of improved depth resolution which results in better background discrimination. A new concept of Raman imaging is also presented which benefits from the confocal system and overcomes most of the limitations of direct imaging techniques. A dual fibre‐optic remote analysis scheme is described which has been developed to optimize the collection of the scattered light while minimizing the interference from the optical fibres.
Near‐infrared Fourier transform Raman spectroscopic study of human brain tissues and tumours
Authors: Mizuno A. , Kitajima H. , Kawauchi K. , Muraishi S. , Ozaki Y.
Published: May 2005

Non‐destructive examination of human brain tissues and several kinds of brain tumours using near‐infrared (1064 nm) excited Fourier transform (NIR‐FT) Raman spectroscopy is reported. The spectra from normal but edematous grey and white matter were similar to those of normal rat grey and white matter reported previously. The brain tumours investigated (glioma grade II and III, two acoustic neurinomas and central neurocytoma) gave Raman spectra essentially the same as to that of grey matter. Histological examination of glioma grade III revealed extracellular PAS‐positive materials, which have a band at 856 cm−1due to polysaccharides. One of the neurinoma contained a carotenoid which exhibited two resonance Raman peaks at 1157 and 1524 cm−1; another neurinoma did not contain the carotenoid. The appearance of a strong Raman peak at 960 cm−1suggested that the central neurocytoma of choroid plexus was calcified.
In situ fiber‐optic Raman spectroscopy of organic chemistry in a supercritical water reactor
Authors: Myrick M. L. , Kolis J. , Parsons E. , Chike K. , Lovelace M. , Scrivens W. , Holliday R. , Williams M.
Published: May 2005

In situ measurements were made of several organic chemical reactions in supercritical water using fiber‐optic probes, near‐infrared excitation and CCD array detection. The reactions studied include the conversion of cyclohexene to cyclohexane and benzene in the presence of a platinum catalyst, conversion of cyclohexanol to cyclohexene in the presence of a cobalt catalyst and the homopolymerization of styrene. Transition to the supercritical state was marked by a sudden decrease in the background and the appearance of intense Raman bands for dissolved organic compounds. The results indicate that this method of study is both sensitive and rapid enough to permit kinetic measurements, even when reactions are completed in less than 2 min.
Raman and infrared spectroscopic study of the molecular characterization of the biocompatibility of prosthetic biomaterials
Authors: Bertoluzza A. , Fagnano C. , Tinti A. , Morelli M. A. , Tosi M. R. , Maggi G. , Marchetti P. G.
Published: May 2005

Raman spectra were obtained directly in a non‐destructive and non‐invasive way from the biomaterials PMMA [poly(methyl methacrylate)], HDPE (high‐density polyethylene), α‐Al2O3 (alumina) and HA (hydroxyapatite) constituting the components (bone cement, acetabular cup, ball and stem coated with ceramic) of a hip prosthesis. The aim was to give an objective contribution at a molecular level to predict their biocompatibility. In particular, Raman spectra of explanted PMMA bone cements do not show the 1640 cm−1 band due to the stretching mode of CC unsaturated centres. Moreover, conformational changes of PMMA following the implant appear in the spectra in the range 1100‐500 cm−1, where conformational marker bands at 985, 968, 601 and 565 cm−1 are present. The limited number of HDPE explanted acetabular cups did not allow unequivocal Raman results to be obtained by means of band deconvolution in the region between 1500 and 1000 cm−1, regarding the changes in the crystalline, amorphous and interfacial contents of the acetabular cup surfaces following the implant. α‐Al2O3 proved to be a ceramic with good biocompatibility as a biomaterial constituting a hip prosthesis. As regards the stem coating, Raman and Fourier transform IR spectra of HA pre‐coating and HA coating on metal implants show spectroscopic modifications due to structural and chemical changes with formation of other calcium phosphates. The development of new bioactive coatings containing precursors of bone growth and able to promote osteogenesis is outlined.
Vibrational spectra of β‐LiVOPO4 and NaVOPO4
Authors: Baran Enrique J. , Vassallo Marta B. , Lii Kwang‐Hwa
Published: May 2005

The infrared and laser Raman spectra of β‐LiVOPO4 and NaVOPO4 were recorded and are briefly discussed with the aid of factor group analyses, based on recently reported structural data. Some spectroscopic features related to the characteristics of the VO and PO bonds in these compounds are also commented upon.
Vibrational spectra for purine and its 15N‐ and D‐substituted analogues. Assignment of normal modes from ab initio 3–21G force fields
Authors: Majoube M. , Henry M. , Vergoten G.
Published: May 2005

Fourier transform (FT) IR and FT‐Raman spectra for purine and its N‐, C8‐ and N‐ and C8‐deuterated analogues and for that 15N‐substituted on the pyrimidine ring are reported. Experimental data are interpreted by reference to ab initio‐calculated wavenumbers for normal modes of both N7H‐ and N9H‐purines. The latter were obtained from normal coordinate analyses carried out on the basis of ab initio 3–21G force fields using the optimized geometry. The effect of hydrogen bonding on the discrepancy between calculated and observed wavenumbers for normal modes was analysed. Considering the solid N7H‐purine, the observed 15N shifts for FT‐IR bands often agree with those calculated for the corresponding normal modes. Several weak bands are tentatively assigned to the N9H tautomer, presumably present in small amounts in solution and also in the solid in the case of deuterated purines.
Vibrational spectral analysis of Eosin Y and Erythrosin B—intensity studies for quantitative detection of the dyes
Authors: Narayanan V. Anantha , Stokes David L. , Vo‐Dinh Tuan
Published: May 2005

The complete vibrational spectra of Eosin Y and Erythrosin B were recorded using Fourier transform Raman and Fourier transform infrared spectroscopy. The surface‐enhanced Raman scattering (SERS) spectra of these two dyes were also studied using an intensified charge‐coupled detector (ICCD) Raman spectrophotometer operated with 5 mW laser power. The intensities of the intense alternating CC bond wavenumbers of the aromatic ring at 1333 cm−1 in Eosin Y and 1317 cm−1 in Erythrosin B were measured as a function of the analyte concentration of these dyes. Calibration graphs of concentration of the dyes in ethanol solution against photon counts are presented. The limits of detection of these two bands in the SERS spectra were determined.
Deconvolution of lorentzian Raman Linewidth: Techniques of polynomial fitting and extrapolation
Authors: Singh Ranjan K. , Singh S. N. , Asthana B. P. , Pathak C. M.
Published: May 2005

A simple, convenient and precise technique for deconvolving the Lorentzian (true) Raman linewidth, ΓL, from the observed Raman linewidth, (Δ1/2)R [the FWHM (full width at half‐maximum) of the Raman line in question], through polynomial fitting, was developed. The precision of this technique is a consequence of the fact that the values of ΓL/(Δ1/2)R (= Y), obtained by exact numerical evaluation of the Voigt profiles for the Raman bands, were flitted to third‐ and fourth‐degree polynomials in S/(Δ1/2)R (= X), S being the spectral slit width measured as the linewidth (FWHM) of a narrow spectral line recorded at the same slit settings as the Raman line. The procedure of obtaining ΓL, from the knowledge of S,(Δν1/2)R and X, which yields better results, is discussed. Another technique of deconvolution is described and discussed, involving the measurement of Raman linewidths of a particular Raman line for about five or six different slit widths. The measured linewidths (Δ1/2)R, when extrapolated to S → 0, give the value of ΓL directly. A careful comparison with the other deconvolution techniques reveals that the method of polynomial fitting is relatively more precise than other semi‐analytical deconvolution techniques, and the extrapolation technique also gives reasonably good results. The applicability of both methods was tested by taking some selected Raman lines.
Optical and resonance Raman scattering study of two ‘bisazo’ pigments derived from substituted benzene‐2′‐azonaphthols
Authors: Sourisseau C. , Maraval P.
Published: May 2005

The UV‐visible (300–800 nm), Raman and resonance Raman (900–1700 cm−1) spectra of two bisazo scarlet RN and brown 5R pigments have been investigated in the solid state at 300 K. A detailed analysis of the resonance Raman spectra and excitation profiles of various fundamentals in the 900–1700 cm−1range is reported through the visible absorption spectrum region: the vibrational assignments confirm that both substituted benzene‐2′‐azonaphthol derivatives are stabilized in their hydroxyazo form; the excitation profiles (EPs) established for many modes in each dye indicate interferences between two overlapping electronic manifolds. Taking account of multistate interference phenomena and inhomogeneous broadening effects, the observed EPs compare well with the calculated ones under the assumption of weakly displaced harmonic oscillators; this interpretation is supported by the observation of weak overtone and combination bands in the 1700–3000 cm−1range.

Finally, conclusions are drawn about the scattering mechanisms and the nature or degree of mixing of the first electronic excited states, which appear to be quite sensitive to the substituent (Cl or NO2) on the benzene rings. Such information can be helpful for the design and synthesis of new azo dyes with desirable properties.
A resonance Raman polarization study of the mode‐specific subpicosecond photodissociation of the NO2 22B2 state
Authors: Fan R. , Ziegler L. D.
Published: May 2005

Vibronically specific subrotational period lifetimes of the predissociated 22B2 state of NO2 vapour (250–235 nm) have been determined by spontaneous resonance Raman scattering polarization measurements. The lifetimes of the vibronic symmetric stretching, ν1′, (100), bending, ν2′, (101), and asymmetric stretching, ν3′, (002), overtone levels are 75 ± 10 fs, 2.5 ± 05 ps and 155 ± 15 fs respectively. When one quantum of bending (ν2,′) is excited in combination with one quantum of totally symmetric stretching (ν1′), the lifetime increases from 75 ± 10 to 125 ± 15 fs (110). The 22 B2 state electronic origin lifetime has been previously shown to be 42 ± 5 ps independent of angular momentum quantum numbers. These results are interpreted in terms of the shape of the potential energy surface intersections in the region and the results of earlier quantum yield measurements.
Adsorption of 4‐hydroxybenzoic acid on silver investigated by surface‐enhanced Raman scattering
Authors: Kwon Yong Joon , Park Sung Soo , Kim Kwan , Kim Myung Soo
Published: May 2005

Surface‐enhanced Raman scattering (SERS) of 4‐hydroxybenzolc acid (4HBA) was investigated in a silver sol and at a silver electrode. The adsorption behaviour of 4HBA on the sol surface appeared different from that on the electrode surface. It was concluded that the molecule binds to the sol particle surface as either oxidobenzoate or hydroxybenzoate assuming a flat orientation. The former species that was bonded to silver via both the lone pair electrons of the oxido group and the π orbitals of the carboxylate group was more stable in a basic environment On the electrode surface, the molecule seemed to bind as hydroxybenzoate mainly through the oxygen lone pair electrons of the carboxylate group, with the hydroxyl group being pendent to the surface. From the pH dependence of the SER spectral pattern, the acid strength of the hydroxyl group was estimated to become 104 times stronger on the sol surface in comparison with that in the bulk. The nature of the different adsorption mechanisms observed on the sol and electrode surfaces is not yet certain. Tentatively, the difference was attributed to the different surface morphology along with the intrinsic difference in the nature of SERS active sites on the two surfaces.
Vibrational spectroscopic studies of aqueous dextran sulphate
Authors: Siew Diana C. W. , Cooney Ralph P. , Taylor Michael J. , Wiggins Philippa M.
Published: May 2005

The interaction between water and polyelectrolytes was investigated using aqueous dextran sulphate systems. The results indicated that the hydrogen‐bonding network of water in the system is affected by the presence of a highly charged polyanion with both surface hydrophobic and hydrophilic sites. This is reflected in the spectral profile of the OH stretching mode of water in the region 3000–4000 cm−1. Comparison with aqueous sodium methyl sulphate and sodium sulphate systems suggests that two regions of water are present in the dextran sulphate system. Water in the region associated with the hydrophobic carbohydrate skeleton appears to be more strongly hydrogen bonded than bulk water whereas that in the vicinity of the hydrophilic SO3 − groups is more weakly hydrogen bonded. Variations in the vibrational spectra were dependent on the extent of the different populations of water present and can be explained by invoking the concepts of long‐range intermolecular coupling. Analysis of the dextran skeletal bands in the region 750–1850 cm−1 confirmed that the SO3 − sites play an important role in the hydration of dextran sulphate. The presence of two symmetric SO3− stretching modes in the Raman spectra of these systems, both of which are sensitive to the hydration state of the molecule, has been explained in terms of a model based on non‐equivalent SO3 − sites.
Raman excitation profiles of metal dithiolenes: Comparison between the transform method and time‐dependent theory
Authors: Ribeiro M. C. C. , Barreto W. J. , Santos P. S.
Published: May 2005

The time‐dependent theory of the resonance Raman effect was employed for the calculation of the Raman excitation profiles and optical absorption spectra of the meial dithiolene species [Zn(dmit)2]2− and [Ni(dmit)2]2− (dmit = 4,5‐dimercapto‐1,3‐dithiolc‐2‐thionc) The model adopted takes into account the three normal modes notable for their enhancement at resonance, and embodies the linear non‐Condon coupling contribution. Previous calculations for these species using the transform method lead to estimates of the relative displacements of potential surface minima for the three modes considered, while the present calculations led to absolute values for such displacements. The metal‐sulphur bond length is increased by 0.016 and 0.027 Å in the zinc and nickel complexes, respectively.
Raman spectroscopic study of ion association in aqueous magnesium sulphate solutions
Authors: Rull F. , Balarew Ch. , Alvarez J. L. , Sobron F. , Rodriguez A.
Published: May 2005

A Raman spectroscopic study of aqueous solutions of MgSO4as function of concentration and temperature was performed. From the analysis of the band profile of the internal vibrations of the sulphate ion, the spectroscopic ionic association constant was calculated at different temperatures. It was found that the association is solvent separated in the ranges of concentration and temperature studied. The large differences observed between the values obtained for the spectroscopic association constant and those obtained from macroscopic measurements were interpreted on the basis of a four‐step solvent‐separated dehydration mechanism. It is, assumed that the Raman spectra reflect only the short‐distance force acting on the sulphate anions. The contribution of the long‐range forces for the consecutive steps were calculated using the Bjerrum equation. Good agreement between the overall association constant thus calculated and the macroscopic value was found in the concentration and temperature ranges studied.