Journal of Raman Spectroscopy

Raman optical activity (ROA) is a relatively new technique used to determine the structure of chiral molecules and is proving useful in the study of biological molecules. Here, for the first time, we demonstrate the applicability of ROA as a technique to study achiral groups in chiral environments, detecting the induced chiralty of N-(fluorenyl- 9-methoxycarbonyl) (Fmoc) in a chiral self-assembled structure of Fmoc-dipeptides. This technique is therefore of interest to those studying self-assembled systems that adopt a chiral structure.

The molecular structure of the uranyl mineral rutherfordine has been investigated by the measurement of the NIR and Raman spectra and complemented with infrared spectra including their interpretation. Raman spectra show the presence of four sharp bands at 3511, 3460, 3329 and 3151 cm⁻¹. Corresponding molecular water bending vibrations were only observed in both Raman and infrared spectra of one of two studied rutherfordine samples.

A complete vibrational analysis of 1,3-dibromo-2,4,5,6-tetrafluoro benzene (DTB) and 1,2,3,4,5-pentafluoro benzene (PB) was performed by combining the experimental and theoretical information using Pulay's density functional theory (DFT) based on scaled quantum chemical approach.

The intermolecular interactions in amylose/dimethyl sulfoxide complexes are discussed both experimentally and theoretically by means of Raman and infrared spectroscopies. Based on the analysis of pure DMSO and DMSO-H₂O mixtures, the investigation is extended to amylose complexes where Raman spectroscopy in the CS stretching wavenumber range reveals a high sensitivity to the strength and to the type of interaction involving the DMSO molecules.

Tellurates are rare minerals as the tellurate anion is readily reduced to the tellurite ion. Often minerals with both tellurate and tellurite anions are found. An example of such a mineral containing tellurate and tellurite is yecoraite. Raman spectroscopy has been used to study the mixed anion mineral yecoraite Bi₅Fe₃O₉(Te⁴⁺O₃)(Te⁶⁺O₄)₂·9H₂O.

The FT-Raman and IR spectra were used to investigate dye Martius yellow sodium salt monohydrate (MYM). The vibrational analysis explicate the conjugation or charge transfer interactions of the molecule supported by using the scaled quantum mechanical (SQM) force field technique based on density functional theory (DFT) calculations. A natural bond orbital analysis (NBO) was performed to demonstrate various intramolecular interactions that are responsible for the stabilization of this molecule leading to its bioactivity.

In spite of detailed structural characterization of nanoscale carbons, they still possess some features that are not entirely understood particularly in terms of topological characteristics. By means of resonance Raman spectroscopy, we elucidated the notion of global topology and curvature by determining the prominent Raman bands variation for various carbon nanostructures including tubular (single-, double- and multiwalled nanotubes, peapod), spherical (hypo- and hyperfullerenes, onion-like carbon) and complex (nanocones, nanohorns, nanodisks and nanorings) geometries. This knowledge points to an unprecedented emergent paradigm of global topology/curvature → property → functionality relationship.

Hydrotalcites of formula Mg₆(Fe,Al)₂(OH)₁₆(CO₃)·4H₂O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio have been successfully synthesised. Raman and infrared bands in the OH stretching region are assigned to (1) brucite layer OH stretching vibrations, (2) water stretching bands and (3) water strongly hydrogen bonded to the carbonate anion.

By using Raman scattering spectroscopy we have studied the (1 − x)PMN–xPT relaxor close to the morphotropic phase boundary. By analyzing the temperature-dependent Raman spectra, we observed a temperature-induced structural phase transition at 170 K for x = 0.4. Lattice dynamics phonon calculations enable us to interpret the complex Raman signature of the (1 − x)PMN–xPT relaxor.

By using Raman scattering spectroscopy we have studied RbBi_1/3W_8/3O₉ (RBW) hexa-tungstate under hydrostatic pressure. This material undergoes a pressure-induced structural phase transition at about 4 GPa associated with rotations of octahedral units along the hexagonal axis. Lattice Dynamics Phonon calculations revealed tubular-like vibrations of oxygen atoms in the hexagonal cavities of the K_0.26WO₃ prototype structure (see Figs 1 and 2). These modes play a fundamental role in the structural instabilities of RBW under hidrostatic pressure.

The concerted use of resonance Raman spectroscopy and CASSCF/CASPT2 calculations revealed the intramolecular charge transfer (ICT) nature of the lowest energy electronic transition in the dianionic form of 4-(4-nitrophenylazo)resorcinol. The two extra negative charges generate a chromophoric unit that shows one of the lowest ICT energies observed (λ_max = 630 nm) in this class of push–pull molecular systems.

Ultraviolet resonance Raman spectroscopy is used to identify the vibrational signatures of conformational changes in stacked bases due to the locked ribose in LNA. These data suggest that the conformation of LNA is dominated by imidazole–imidazole and pyrimidine–pyrimidine repulsion and imidazole–pyrimidine attraction in contrast to dispersion attraction-dependent aggregation in the B-form of DNA.

We describe quantum-size and binding-site effects on the chemical and local field enhancement mechanisms of surface-enhanced resonance Raman scattering (SERRS), in which the pyridine is adsorbed on one of the vertices and surface of Ag₂₀ tetrahedron, respectively. The influence of the binding-site and quantum-size effects on NRS, as well as chemical and electromagnetic enhancement mechanisms on SERRS, is significant.

Raman spectra from (GaP)_n/(InP)_n short-period superlattice structures were investigated to study the effect of lateral composition modulation (LCM) on the behavior of optical phonons. We observed a significant increase of the InP- and the GaP-like longitudinal optical phonon energies related to the formation of LCM. A broadening of the phonon line shapes was also observed.

The vibrational analysis of 1,4,5-triazanaphthalene was carried out using Pulay's DFT-based scaled quantum mechanical (SQM) approach. The observed and calculated wavenumbers agree well. The various vibrational modes are discussed in detail.

We propose a simple method to synthesize different morphologies of gold nanostructures by solar radiation, which can then be used as SERS substrates with p-aminothiophenol as the probe molecule. The flowerlike gold nanostructures show the strongest SERS effect.

We combined laser tweezers and Raman spectroscopy to study the response of a single cell to oxidative stress. By means of sequential spectral measurements, we identified lipid peroxidation occurring during oxidative injury and demonstrated the therapeutic effect of ascorbic acid to such injury at the molecular level.

With a five-component Gaussian deconvolution of the Raman spectra of aqueous solutions of NaCl, MgCl₂, AlCl₃ and FeCl₃, the cationic effects are found to be similar on the components at 3233, 3393, 3511 and 3628 cm⁻¹, but different on component at 3051 cm⁻¹. All the metal ions break the water structure, and the ions with more ionic charges have a strong influence on oxygen of water and make strong hydrogen bonds.

In this work, we have performed Raman scattering measurements in Ba₂BiSbO₆ ceramics in the temperature range from 10 to 573 K. The Raman spectra were examined using group theory to analyze the decomposition of the reducible representation of the vibrational modes and with a virtual octahedra model. Both structural phase transitions that this compound exhibits were subtly observed.

FT-Raman and FT-IR spectra of 4-chloro-2-(4-bromophenylcarbamoyl)phenyl acetate were recorded and analyzed. The vibrational wavenumbers of the title compound have been computed using the B3LYP/6-31G* basis and compared with the experimental data. The simultaneous IR and Raman activations of the CO stretching mode gives the charge transfer interaction through a π-conjugated path. The assignments of the normal modes are done by PED calculations.

Lutetium yttrium orthoaluminate perovskite [Lu_0.7Y_0.3AlO₃ (LuYAP)] crystals show great potential as fast response and high-efficiency scintillators. This paper offers a complete analysis of the vibrational modes of the LuYAP crystal by polarized Raman spectroscopy in the temperature range of 20-290 K and compares the experimental results with numerical methods in order to characterize the crystal structure. An interpretation of the data in terms of vibrating molecular structures is suggested and the results are successfully confronted with the vibrational modes of similar perovskite crystals.

An optical parametric oscillator (OPO) is an ideal tunable light source for coherent anti-Stokes Raman scattering (CARS) spectroscopy. An OPO specially designed for high-resolution CARS spectroscopy in the fingerprint region is presented here. The first results of applying the maximum entropy method of phase retrieval to narrowband CARS spectroscopy, in order to retrieve the purely resonant CARS spectrum, are shown.

Calcification of bone and cartilage is a complex process. Noncollageneous proteins such as fetuin and osteocalcin (BGP) interact with the growth of HA crystals and control the size of the calcospherites. These proteins, which are present in small amounts in the medium used for crystal growth, can be found adsorbed onto the HA calcospherites by Raman microspectroscopy.

At least 17 different minerals in the ceramic body were identified from the Raman spectra, among which were a variety of feldspars, as well as andradite, apatite and forsterite. According to the identified minerals, the locations of the used raw materials in the vicinity of the archaeological sites are proposed. There is a good correlation between the polymerization index derived from the Raman spectra and the lead content obtained from the SEM-EDXS analyses; thus the firing temperature of the analyzed glazes could be assessed.

An anomalous lineshape of stimulated Raman spectra obtained from the region very close to the nozzle of supersonic pulsed expansions of N₂ is presented. The combination of Doppler shifts and strong gradients of density and temperature yield an inhomogeneous broadening and a double-peak structure of the recorded Raman line profiles. Their comparation with simulations provides information about the near-nozzle flow field. This lineshape is not related to effects of clustering on the jet axis.

Red blood cells are stretched using optical tweezers while simultaneously recording their Raman spectrum. The depolarization ratios of the heme Raman bands change upon stretching, which indicates the existence and deformation-induced altering of protein ordering in the cell. The result points to a larger role of deformation in the functionality of the red blood cell.

FT-Raman and FT-IR spectra of 3-{[(2-hydroxy-phenyl)methylene]amino}-2-phenylquinazolin-4(3H)-one were recorded and analyzed. The vibrational wavenumbers of the title compound were computed using the HF/6-31G* basis and compared with the experimental data. The prepared compound was identified by NMR and mass spectra. The simultaneous IR and Raman activation of the CO stretching mode gives the charge transfer interaction through a π-conjugated path. The assignments of the normal modes are done by potential energy distribution calculations.

SERS experiments were carried out to understand the structure of L-glutathione monolayers on a silver surface and the impact of Pb²⁺. In presence of Pb²⁺, the adsorption mode of L-glutathione on the silver surface changed from mercapto group along with imine, amino and entire carboxyl groups as the direct co-adsorption sites to mercapto and imine (N3H) groups as the anchoring sites.

The collective properties of liquid tert-butyl alcohol were analysed by low-wavenumber Raman scattering spectroscopy. Vibrational and relaxation phenomena of this H-bonding system were assessed in pure liquid phase and in solution with 2,2′-dimethyl butane and water.

Raman spectroscopy is a powerful tool for chemical analysis. Its advantages are well known for the investigation of food quality. In our work, we demonstrate that Raman spectroscopy using visible laser excitation is capable of differentiating between olive oil and 13 types of vegetable oils and detecting adulterations of virgin olive oil with high reliability and sensitivity.

High quality of SERS spectra from 4-mercaptopyridine (4-Mpy) molecules adsorbed on sub-monolayers of α-Fe₂O₃ nanocrystals (sphere, spindle, cube) have been recorded. 4-Mpy molecules are adsorbed on the surface of substrate through the sulfur atom at a perpendicular orientation. The charge transfer mechanism is suggested as most likely responsible for the observed enhancement as plasmon resonances do not occur.

Arterial hypertension is treated with non peptide antagonists of the receptor of the enzyme angiotensin II such as Irbesartan. Irbesartan exists in two tautomeric forms. The infrared and Raman spectra using a mixture of both forms, as supplied, were recorded and discussed assisted with density functional theory (6-31G** basis set, animated pictures). ¹³C, ¹⁵N and ¹H NMR together with vibrational theoretical studies allowed the determination of the main features of the A and B tautomers.

A novel quartz cell is presented here for monitoring H/D exchange in biomolecules by using Raman spectroscopy. This cell is combined with a syringe to pump heavy water through a hollow microdialysis fibre, which is inserted into the cell. The fastest D₂O efflux that we have obtained permits to measure exchange rates of 2.5 min⁻¹ or less.

The SERS spectrum of 4-methyl-4H-1, 2,4-triazole-3-thiol reveals the adsorption fashion via S⁶ and N² atoms to form monolayers on the silver surface. Electrochemical experimental results exhibit a sound anticorrosive feature of 4-methyl-4H-1, 2, 4-triazole-3-thiol monolayers for silver.

The significant intensity enhancement in the B-band (282.4 nm) resonance Raman spectrum of the nominal SCS antisymmetry vibrational modes (υ₁₄) of ethylene trithiocarbonate relative to A-band (319.9 nm) and FT-Raman spectra suggest a possible existence of the vibronic coupling in the B-band absorption.

Ag colloids were prepared by the microwave heating method. The UV-visible spectrum and transmission electron microscopy (TEM) were employed to characterize the Ag colloids. The surface-enhanced Raman scattering (SERS) spectra of chloramphenicol (CAP) in Ag colloids were successfully recorded. The Raman spectra of CAP were recorded with good concordance comparing to the theoretical results calculated by the Gaussian'98 program. CAP molecules on the Ag surface are oriented tilted to the particle surface via C20-O23, N-O13, and N-O23, which played an important role in the SERS effect.

The tip-enhancement of resonance Raman scattering for DUV excitation wavelength was demonstrated for the first time using an aluminum tip that acts as a plasmonic material in DUV wavelengths. With results demonstrated here, molecular analysis and imaging with nanoscale spatial resolution in DUV resonance Raman spectroscopy can be realized using the tip-enhancement effect.

The absolute Raman scattering cross section of the 1584-cm^{− 1} band of benzenethiol has been measured to be 8.9 ± 1.8 × 10⁻³⁰ cm² using a 785-nm pump laser and a 675 C blackbody for the spectrometer signal calibration. We also measured the surface-enhanced Raman scattering (SERS) enhancement factor (EF) of 0.8 ± 0.3 × 10⁶ for a silver-coated, femtosecond laser-nanostructured substrate.