Journal of Raman Spectroscopy

Ultrafast Raman loss scattering (URLS), a self-phase matched non-linear process, is much more sensitive than stimulated Raman spectroscopy (SRS), the signals are background (noise) free unlike in coherent anti-Stokes Raman spectroscopy (CARS) and it provides natural fluorescence rejection. URLS is expected to be alternative if not competitive to CARS microscopy, which has become a popular technique in applications to materials, biology and medicine.

We demonstrate that Raman spectroscopy is able to discriminate between cross-conjugated (CC) and pseudo-cross-conjugated mesomeric betaines (PCCMBs) by means of key bands sensitive to conjugation. As targets, we have selected the CCMB (1) and its isomer the PCCMB (2). Structurally, they differ only in the position of the carboxylate group bonded to the pyrazolium ring. We evidence that a subtle electronic effect has a measurable impact on the vibrational wavenumbers as Raman spectroscopy can directly account for it.

We report, to the best of our knowledge for the first time, the application of tip-enhanced Raman scattering (TERS), providing vibrational spectroscopic information with a spatial resolution less than 50 nm, to characterize single tobacco mosaic viruses at a molecular level.

The structures of the naturally occurring sulfite-bearing minerals scotlandite, hannebachite and orschallite has been studied by Raman spectroscopy. Raman bands are observed for scotlandite PbSO₃ at 935, 880, 622 and 474 cm⁻¹ and are assigned to the (SO₃)²⁻ν₁(A₁), ν₃(E), ν₂(A₁) and ν₄(E) vibrational modes.

Raman spectroscopy has been used to study the tellurate mineral kuranakhite. A comparison of the Raman spectra with that of tlapallite and xocomecatlite is made.

Vibrational spectroscopic study and ab initio calculation on p-methylbenzaldehyde (PMBz) in three different solvents, namely butanol, 1,2 dichloromethane and carbontetrachloride, have been carried out. The PMBz molecule forms hydrogen bonds through self-association. By examining the peak position and Raman linewidth of the vibrational modes of PMBz the interaction between solute and solvent could be interpreted in terms of solute–solvent interactions.

UV resonance Raman spectroscopy with 229 nm excitation was used to study two tryptophan-containing antimicrobial peptides, lactoferricin B and pEM-2, in complex with lipid vesicles. Results of the study suggest stronger interactions between these cationic peptides and anionic vesicles.

A complete vibrational analysis of benzoic acid and 3,5-dichloro salicylic acid was performed by combining the experimental and theoretical information using Pulay's density functional theory (DFT) based on scaled quantum chemical approach.

The microstructures of (1 − x)(TeO₂)–xPbF₂ (x = 0.1, 0.15, and 0.25 mol) glasses were investigated using Raman spectroscopy. The effect of composition on the TeO₂ glass networks and the intensity ratios of the deconvoluted Raman peaks were determined. The results confirm that the addition of the modifier to the glass network former shifts the Raman intensity and the peak wavenumber values for each band in the 167–165, 652–645, and 747–755 cm⁻¹ wavenumber regions. The structural evaluation was recognized from the Raman spectra with the structural units described as [TeO₃₊₁] polyhedra, [TeO₃] trigonal pyramids, and [TeO₄] trigonal bipyramids for this binary glass system.

This review emphasizes the understanding of the SERS of bacteria in terms of the nature of the SERS-active centers and their placement within the bacterium. On the interpretation and assignment of the spectra, we constantly keep in mind the final goal of bacteria identification.

The infrared and Raman spectra of bromotrimethylgermane (BTMG) were newly recorded to complete the assignment of its vibrational spectra. Low temperature infrared techniques together with the FSD on the Raman spectrum were used to improve the resolution of the spectra for the modes that could not be observed before.

In the field of pharmaceutical analysis the focus is mainly on the active ingredient and hardly any attention is paid to the excipients present. This reference database presents the Raman spectra of 43 commonly used excipients and identification of the Raman bands. These excipients are divided into seven groups on the basis of the chemical composition. These groups include mono- and di-saccharides, polysaccharides, polyalcohols, carboxylic acids and salts, esters, inorganic substances and others.

The use of a micro Raman-setup in combination with the silver colloid enables us to investigate the essential oils of Mentha in the glandular scales itself. Preliminary results from our investigation of the identification of mint Taxa are represented. The identification of the individual Taxa is supported by the cluster analysis.

The spectroscopic (IR and Raman) investigation of a new crystal of sarcosine: (CH₃NH₂⁺CH₂COO⁻)₃ċBaBr₂ (TSBB) was performed at room temperature and compared with the crystallographic data and with the results obtained previously for TSCC crystal. TSBB crystallizes in the monoclinic system, space group P2(1)/c and possesses a pseudohexagonal symmetry down c axis. It undergoes a PT at 416 K (heating)–415 K (cooling).

2-Piperidyl-5-nitro-6-methylpyridine (PNMP), has been synthesised and characterised by means of FTIR and Raman spectroscopies, DSC and single-crystal X-ray crystallography. The assignment of the observed bands has been proposed. X-ray diffraction studies have shown that PNMP undergoes a structural phase transition at T = 240 K.

Raman spectroscopy is used to study the microstructures of MnSi_x thin films annealed at different temperatures. Two phases of Mn silicides, MnSi_1.73 and MnSi, are identified, and their Raman spectra reported. Each phase of Mn silicides shows a set of three well-defined peaks at about 300 cm₋₁ in the spectrum, which could be used as fingerprints in identifying the formation of Mn silicides.

Mixed Na₂SO₄/MgSO₄ aerosol droplets on a quartz substrate were investigated in their evaporation processes by a micro-Raman system. Phase separations in the droplets were studied in detail. In the figure, the Raman spectra (right) show that the small crystals precipitated from the 1:1 Na₂SO₄/MgSO₄ droplet are in form of anhydrous Na₂SO₄ (metastable phase III), which are very different from the Raman spectra (left) of the residual solution surrounding the small crystals.

The Raman spectra of recently synthesised multi-walled carbon nano-tube (MWCNT) filters along with other carbonaceous materials, i.e. single-walled carbon nano-tubes (SWCNTs) and MWCNTs, graphitised porous carbon (Carbotrap) and graphite, have been recorded using excitation wavelengths of 532 and 785 nm and analysed for band positions and line shape with special emphasis on the D-, G- and G'-bands. On the basis of the findings of this study, Raman spectroscopy yields a good parameter, I_D/I_G to check the degree of alignment in a MWCNT bundle and hence may prove to be a reliable and quick method of quality control during fabrication of aligned MWCNTs.