Thermal decomposition Raman spectroscopy

Thermal decomposition (with generation of neutral sulfur species, e.g., of 82,). The main gaseous product of thermal decomposition at rather low temperatures (100-200°C) of Cs2[Mo2(82)6]-reH20 is the 82 molecule, which results by reductive elimination. This has been proved by mass spectroscopy and matrix isolation Raman, UV/VI8, and IR spectroscopy (67,107). 

Extensive characterisation studies have been performed with various techniques (XAFS, XPS, 31P CP/MAS-NMR, IR and Raman spectroscopies)13 to characterise Aul after deposition, and its decomposition and conversion into metal particles upon thermal treatment. The transformation of hydroxide supports into oxides was also followed. The amorphous hydroxides contain a larger number of surface hydroxyl groups and surface defects than do the corresponding oxides, and they interact more efficiently with Aul, which dissociates on the surface, releasing the... 

The thermal decomposition studies were initially carried out by following weight-loss as functions of time and temperature of the sample when under vacuum. When the lowest temperature for rapid weight-loss had been established it was our practice to hold the sample at this temperature until constant weight was attained. The volatiles were trapped at -196° and were subsequently examined by gas-phase Infrared spectroscopy. The residual solids in the Monel tubes were examined by X-ray powder photography, Raman and Infrared spectroscopy and were also tested for para- or diamagnetism. 

The Raman spectra of carbon nitride nanotubes show evidence for a high degree of graphitisation.294 Raman spectroscopy was used to characterise CNX nanotubes formed by the thermal decomposition of ferrocene/ethylenediamine mixtures. 

IR spectroscopy was used to determine the morphology of W03 powders formed by thermal decomposition of tungstic acids.220 IRRAS and Raman data were used to characterise amorphous and crystalline W03 thin films.221 Raman spectroscopy could be used to follow changes to W03 electrochromic thin films during electrochemical cycles.222... 

Perez-Ramirez, J., Mul, G. and Moulijn, J. A. (2001). In situ Fourier transformed infrared and laser Raman spectroscopic study of the thermal decomposition of Co-AI and Ni-Al hydrotalcites. Vibrational Spectroscopy, 27,75-88. 

The sample must be placed at the focal point of an intense laser beam, and some samples may be subject to thermal decomposition or photodecomposition. Accessories that spin the sample tube or cup are available, to distribute the laser beam over the sample and reduce heating of the sample. Spinning or rotating the sample minimizes thermal decomposition, but does not stop photodecomposition. Sample spinning is required for resonance Raman spectroscopy, discussed later. 

The Fe =0 stretching mode, Vpe=o> was observed at 852 cm" (818 cm" for 0) by Nakamoto et al. for Fe(TPP) in an oxygen matrix using Raman spectroscopy The Fe =0 derivative was produced by photolysis of Fe(TPP)02. A similar band was observed at 843 cm" for a toluene solution of FeO(TMP) (TMP tetramesityl porphy-rin) which was generated by thermal decomposition of the p-peroxo-bridged Fe porphyrin complex These are for the five-coordinate complexes, but the Vp o mode for the six-coordinate complexes was observed at lower frequencies 829 cm" for FeO(TpivPP)(THF) and 807 cm" for FeO(TpivPP)(l-MeIm). The iron(IV) porphyrin is an important intermediate in a catalytic cycle of peroxidase, for which the RR band due to the Vpe=o mode is identified at 787 cm" Interestingly, the oxygen atom of the... 

B. Pettinger, X. H. Bao, I. Wilcock, M. Muhler, R. Schlogl, and G. Ertl, Thermal-Decomposition of Silver-Oxide Monitored by Raman- Spectroscopy — From AgO Units to Oxygen-Atoms Chemisorbed on the Silver Surface, Angew. Qiem. Int. Ed. Engl. 33, 85 (1994)... 

A mixture of Ni°/NiO, produced by thermal decomposition of nickel acetate, dispersed on either silica or cordierite supports, was found to be catalytically active for the decomposition of methane without the need for any pre-treatment. Other authors used Ni catalysts supported on zirconia to produce H2 and a high yield of multiwalled carbon nanotubes. Raman spectroscopy suggested that carbon nanotubes formed at temperatures higher that 973 K had more graphite-like structure than those obtained at lower temperatures. They also reported that feed gas containing methane and hydrogen caused slow deactivation of the catalyst, and carbon yield increased with increasing Hg partial pressure in the feed gas. For a commercial Ni catalyst (65% wt Ni supported on a mixture of silica and alumina) it was found that catalyst deactivation depends on the... 

Coupling between molecular processes and morphological changes is one of the most unique and important characteristics of laser ablation. Excitation energy relaxation dynamics and primary chemical processes of organic molecules in laser ablation have been investigated by using various time-resolved spectroscopies, such as fluorescence, absorption, Raman and IR spectroscopies. Laser ablation leads to rapid temperature elevation of the polymer matrix and thermal decomposition of the polymer. Ablation causes not only photochemical reactions but also photo-initiated thermal reactions. 

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