Diffuse reflectance infra red Fourier

Among the more recent contributions to this field, some [32-35] call upon the use of new characterization techniques, like diffuse reflectance infra red fourier transform (DRIFT) and cross polarized magic angle spinning (CP-MAS) C-NMR spectroscopy. 

Diffuse Reflectance Infra-Red Fourier Tranfform Spectroscopy. Spectra were acquired in situ using a DRIFT accessory (Collector) equipped with an environmental cell (Spectratech). DRIFT spectra were recorded in nitrogen up to about 500°C (to avoid absorption bands due to physisorbed or hydrogen-bridged water) on a Perkin Elmer 1600 FTIR spectrometer (64 scans, resolution 8 cm- ). 

Venter JJ, Vannice MA. Diffuse reflectance infra-red Fourier transform spectroscopic investigation of the decomposition of carbon supported iron carbonyl clusters. J Phys Chem 1989 93 (10) 4158-4167. 

Diffuse Reflectance Infra-red Fourier Transform Spectroscopy (DRIFTS) is a form of FT-IR that can provide bonding information and concentration if the snr-face coverage is > 1 X 10 atoms/cm of atoms/molecules adsorbed on high snrface area solids, i.e. finely dispersed catalysts. This technique does so by sampling photons experiencing diffuse reflectance. In this mode, some fraction of the photons impinging on a surface are transmitted into the solid. These photons may then be absorbed, further transmitted, or reflected out of the solid. The surface-reflected and bulk re-emitted components, which when summed, represent the recorded signal. No prior sample preparation is required, and analysis can be carried out under ambient conditions. 

DRIFTS Diffuse Reflectance Infra-red Fourier Transform Spectroscopy... 

DRIFT Diffuse reflectance infra-red Fourier transform... 

The catalysts were characterized using Light Microscopy (LM),Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Diffuse Reflection Infra Red Fourier Transform Spectroscopy (DRIFTS), and Temperature-Programmed Reduction (TPR) The effects of the preparation on the catalytic properties in the H2S oxidation were also assessed. 

Because chemical and structural properties of natural and artificial gems are very similar in this case, the possibilities of Raman and LIBS methods are rather limited. It was found that another laser-based techniques could be very effective for rapid spectroscopic discrimination between natural and synthetic emeralds, rubies, and alexandrite (Armstrong et al. 2000a,b). The first one is DRIFTS (Diffuse Reflectance Fourier Transformed Infra-Red Spectroscopy)... 

Surface area, micropore volume, and pores size measurement was done by using N2 with Micromeritics ASAP 2000 equipment and ASAP 2010 software. Surface acidity was determined from temperature programmed desorption of ammonia (TPD-NH3) and equipment used was Micromeritics 2000. Prior to starting tests, catalyst was dried under 30 ml/min Helium continuous flow at 300 C. The temperature at a rate of lO C/min was increased from 27 C to 650°C under a continuous flow of 30 ml/min Helium. Surface groups were determined using diffuse reflectance fourier transform infra red (FTIR) spectroscopy with Nicolet Magna-IR 560 Spectrometer. The catalyst was dewatered at... 

Llewellyn, P.L., and Theocharis, C.R., A diffuse reflectance Fourier transform infra-red study of carbon dioxide adsorption on silicalite-I, J. Chem. Technol. Biotechnol., 52(4). 473-480 (1991). 

Diffuse Reflectance Fourier Transform Infra Red Spectroscopy. Silica exhibits an absorption band at 3750 cm l caused by the stretching vibration of the free hydroxyl groups at the surface. When the surface is covered with active material, this absorption drops, thus providing information about the coverage of the silica surface [6], The catalysts were ground and mixed with potassium chloride (KG < 50 i.m, analytical grade). The thus obtained samples contained S.O wt% of the catalyst. The spectra were taken with a diffuse reflection cell installed in a Perkin Elmer 1600 spectrometer. The spectra were normalized at the symmetric Si-O-Si stretching vibration at t) = 805 cm 1. The area of the peak at 3750 cm was used to estimate the covered silica surface (%). 

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