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Spectral Methods


Nuclear Magnetic Resonance (NMR)

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Electron Paramagnetic Resonance (EPR)

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Electron Ferromagnetic Resonance Spectroscopy

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Ultraviolet-Visual (UV-VIS) Adsorption Spectroscopy, Near Infrared (NIR) Spectroscopy

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Infra-Red Spectroscopy (IRS)

1. Bruker IFS-113V, Shimadzu 8300 Infrared Fourier-spectrometers

Applications

  • Study of the solid surface: surface functional groups, surface acid-base properties, adsorbate functional groups.
  • Quantitative characterization of the surface acid properties.
  • Quantitative analysis of the gases containing aggressive compounds: NO2, SO2, SO3, HCl.

Instrument facilities

Varian FTIR-800 and Bruker Vector-22 IR Fourier-spectrometer are adapted for the study of solid surface. The operating range is 400–7800 cm–1, resolution – up to 1 cm–1, time of 1 spectrum recording is 1 second.

Shimadzu 8300 IR Fourier spectrometer is used for these purposes as well. The operating range is 300–6000 cm–1. Resolution – 1 cm–1, signal/noise ratio is higher than 2000. Time of 1 spectrum recording is 3 seconds. The surface is studied by the methods of in situ transmission (in the temperature range from –196 to +700 oC) and diffusion reflection (from –60 to +200 oC) in the controlled gas mixtures or vacuum.

The determination of gas molecule concentration to 1 ppm in a small pan (lower 50 cm3) is possible.

Additional possibilities

Original methods have been developed for the quantitative measurement of surface acid properties by low-temperature CO adsorption. (E.A.Paukshtis “Infrared spectroscopy in the heterogeneous acid-base catalysis”, Novosibirsk: Nauka, 1992)

An example of IR spectra

An example of IR spectra observed in the course of CO adsorption over H-ZSM-5 zeolite. IR spectra of the initial OH groups are shown by the dotted line. The solid line corresponds to the spectra of OH groups in H-complexes with CO.

From the spectra it is evident that the zeolite is characterised by two types of Lewis acid centers (bands 2217 and 2227 cm–1) and two types of Brönsted acid centers (OH group bands 3294 and 3400 cm–1). Such a subtle difference between acid centers is impossible to register by other methods.

Samples requirements

Weight of the solid sample – 500 mg, for gases – 100 cm3.

2. Bomem M-102 Infrared Fourier-Spectrometer

Applications

  • In solutions: definition of stoichiometric composition and complex compound structure in organic solutions, study of their solvation and hydration, study of the composition and construction of molecular associates (molecular groups, micelles).
  • In solid sample: definition of the phase composition including amorphous phases (coordination metal surroundings, type of the multi-atom ligand and others)
  • On the surface of gas-solid interface: study of the interaction of adsorbed organic molecules with surface; study of the surface intermediates during catalytic reactions, kinetics study (in situ studies).
  • Definition of the defective oxide structure.
  • Estimation of the organic substances concentration in the organic solutions and gas phase. The concentration of non-equivalent (having different surroundings) organic molecules is defined in the complex multi-component solutions.

Instrument facilities

The spectra of gaseous, liquid and solid samples in the frequency range 230 – 4000 cm–1 are acquired by Bomem IR Fourier-spectrometer. The program for spectra analysis allows to acquire high quality spectra for very dilute organic solutions. With CCl4 as a solvent it is possible to study the solutions with the concentration up to 0.5 × 10–3 mol/l.

Additional possibilities

  • Photo-acoustic accessory allowing to record vibration spectra of the surface layer of solids is available .
  • Methods for the study of composition and structure of the individual compounds forming in complex multi-component systems are developed.
  • Development of the methods for estimation of small quantities of organic compounds (petroleum products, phenols and others) in the industrial water exhausts, in sewage and others.

Samples requirements

Weight of solid sample (without considering inert support) – not less than 3 mg.

Volume of solution – not less than 2 ml and solvent used – not less than 2 ml.

For photoacoustic IR spectra acquisition the volume of powdery sample is 1 cm 3.

Bruker Vector-22 IR Fourier-spectrometer

Leading scientists and their research interests

Prof. E.A. Paukshtis. Quantitative basis of the definition of surface acid-base properties, all fields of IR spectroscopy of adsorbed molecules. The author of monograph “Infrared spectroscopy in heterogeneous acid-base catalysis” (in Russian).

Prof. E.S. Stoyanov. Composition and structure of molecular associates and complexes in water and organic solutions, and on the interface of solid-gas, solid-liquid and liquid-liquid.

Dr. E.B. Burgina. Theoretical analysis of experimental vibrational spectra, experimental IR (including NIR) and Raman spectral investigations.

Dr. G.N. Kustova. Analysis of defective oxides structure with IR spectroscopy.

Dr. D.V. Kozlov. Study of the chemical processes on oxides surface (TiO2).


Fluorescent Analysis

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