Fourier Transform Raman Spectrometer Research Articles

Chemical imaging with a confocal scanning Fourier-transform–Raman microscope

Traditional approaches in confocal microscopy have focused on techniques to generate volumetric intensity or phase images of an object. In these different imaging modes the scattered optical-field properties depend on local refractive index and absorption, properties not unique to a given material. We report here on a confocal microscope that uses Raman scattered light to generate volumetric chemical images of a material. We designed and built a prototype instrument, called a confocal scanning laser Raman microscope, that combines a confocal scanning laser microscope with a Fourier-transform-Raman spectrometer. The high depth and lateral spatial resolution of the confocal optics design define a volume element from which the Raman scattered light is collected, and the spectrometer analyzes its spectral content. The sample is scanned through the microscope probe volume, and a chemical image isgenerated based on the content of the Raman spectrum extracted from each scan position in the sample. The results inclu e instrument characterization measurements and examples of confocal chemical imaging.

Process analysis of electroless nickel deposition baths by Raman spectroscopy

AbstractIn a test experiment carried out in a small compact electroless plating facility, the concentrations of hypophosphite and phosphite in a nickel deposition bath of the Kanigen type were monitored on‐line with a dispersive Raman spectrometer. From the results, which agreed with off‐line Fourier transform (FT) IR data within ca. 10%, the molar amounts of nickel, hypophosphite and phosphite consumed and formed were calculated and compared with the stoichiometry of the nickel plating process adopted. In addition, nickel bath samples were also measured with an FT Raman spectrometer to compare the performances of both Raman techniques with a view to their application to aqueous solutions.

Fourier transform Raman spectroscopy of 1,3-dithiole-2-thione and related compounds

The Raman spectra of 1,3-dithiole-2-thione and a series of related compounds were recorded on a fourier transform Raman spectrometer using near-infrared laser excitation. The spectra proved, with limited exception, to be of high quality. With the help of measured depolarisation ratios it has proved possible to make assignments for the stronger peaks in the spectrum of 1,3-dithiole-2-thione, thereby resolving ambiguities and disagreements in the results of previous workers. These assignments have been used to aid in the interpretation of the very characteristic spectra of substituted thiones. The value of these spectra for analytical purposes is 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.

Quantitative analysis using Raman methods

Abstract The feasibility of using a Fourier Transform Raman spectrometer employing back scattering optics, to obtain spectra with excellent reproducibility both in band positions and intensities, is demonstrated. Such a spectrometer affords the basis of quantitative chemical analysis via external intensity standards. The potential and application of the technique are reviewed.

Near-Infrared Surface-Enhanced Raman Spectroscopy. Part II: Copper and Gold Colloids

Near-infrared (NIR) surface-enhanced Raman spectra (SERS) on copper and gold metal colloids were obtained with a Fourier transform Raman spectrometer using a Nd:YAG laser (1.064 μm) for excitation. Enhanced spectra were observed for pyridine and 3-chloropyridine (CP) on copper colloids and for tris(orthophenanthroline)ruthenium(II), Ru(o-phen)32+, on copper and gold colloids. The copper-colloid surface-enhanced Raman spectra of pyridine and CP were compared with spectra measured for these molecules on copper electrodes. NIR-SERS enhancements on the metal colloids were at least as large as for visible-wavelength excited SERS. Good-quality spectra of Ru(o-phen)32+ were obtained at solution concentrations as low as 0.025 mM.

Near-Infrared Surface-Enhanced Raman Spectroscopy. Part I: Copper and Gold Electrodes

Surface-enhanced Raman spectra of pyridine on copper and gold electrodes in the near-infrared were obtained with a Fourier transform Raman spectrometer. Surface-enhanced Raman spectra were observed for pyridine adsorbed on copper and gold electrodes while a Nd:YAG laser (1.064/μm) was used for excitation. Good-quality spectra were recorded for 0.08 mM pyridine on a copper electrode with a single oxidation-reduction cycle, whereas for a gold electrode, several ORCs were necessary. A very intense low-energy Raman band was observed on both metals at positive potentials, which may be due to a metal-oxide vibrational mode.