In-situ Raman spectroscopy

The diffusion, location and interactions of guests in zeolite frameworks has been studied by in-situ Raman spectroscopy and Raman microscopy. For example, the location and orientation of crown ethers used as templates in the synthesis of faujasite polymorphs has been studied in the framework they helped to form [4.297]. Polarized Raman spectra of p-nitroaniline molecules adsorbed in the channels of AIPO4-5 molecular sieves revealed their physical state and orientation - molecules within the channels formed either a phase of head-to-tail chains similar to that in the solid crystalline substance, with a characteristic 0J3 band at 1282 cm , or a second phase, which is characterized by a similarly strong band around 1295 cm . This second phase consisted of weakly interacting molecules in a pseudo-quinonoid state similar to that of molten p-nitroaniline [4.298]. 

However, we have found that reaction induced restructuring of Bi2FeMo20]2 produces a narked enhancement in catalytic behavior (Table II . X-ray diffraction, in-situ Raman spectroscopy, and photoelectron spectroscopy reveal that the restructuring produces a multiphase system consisting of unreacted Bi FeMo20.2, in combination with Bi2MOj0.2, 0-FeHoO and a small amount of Bi2MoO. The key features of the Raman spectra of the activated catalyst are summarized in Table III. 

Pettinger, B., In situ Raman spectroscopy at metal electrodes, in Adsorption of Molecules at Metal Electrodes, 1. Lipkowski and P. N. Ross, Eds., VCH, New York, 1992, p. 285. 

Hess, C. and Lunsford J.H. (2002) Mechanism for N02 Storage in Barium Oxide Supported on Magnesium Oxide Studied by in Situ Raman Spectroscopy,./. Phys. Chem. B, 106, 6358. 

Nowak AM, McCreery RL (2004) In situ Raman spectroscopy of bias-induced structural changes in nitroazobenzene molecular electronic junctions. J Am Chem Soc 126 16621-16631... 

Vibrational spectroscopy techniques are quite suitable for in situ characterization of catalysts. Especially infrared spectroscopy has been used extensively for characterization of the electrode/solution interphases, adsorbed species and their dependence on the electrode potential.33,34 Raman spectroscopy has been used to a lesser extent in characterizing non-precious metal ORR catalysts, most of the studies being related to characterization of the carbon structures.35 A review of the challenges and applications associated with in situ Raman Spectroscopy at metal electrodes has been provided by Pettinger.36... 

Many of the characterization techniques described in this chapter require ambient or vacuum conditions, which may or may not be translatable to operational conditions. In situ or in opemndo characterization avoids such issues and can provide insight and information under more realistic conditions. Such approaches are becoming more common in X-ray adsorption spectroscopy (XAS) methods ofXANES and EXAFS, in NMR and in transmission electron microscopy where environmental instruments and cells are becoming common. In situ MAS NMR has been used to characterize reaction intermediates, organic deposits, surface complexes and the nature of transition state and reaction pathways. The formation of alkoxy species on zeolites upon adsorption of olefins or alcohols have been observed by C in situ and ex situ NMR [253]. Sensitivity enhancement techniques play an important role in the progress of this area. In operando infrared and RAMAN is becoming more widely used. In situ RAMAN spectroscopy has been used to online monitor synthesis of zeolites in pressurized reactors [254]. Such techniques will become commonplace. 

M.A. Banares, In situ Raman spectroscopy, in In Situ Characterization of Catalysts, B.M. Weckhuysen (Ed), American Scientific Publishers, Stevenson Ranch, 2004. 

N.E. Leadbeater and R.J. Smith, Real-time monitoring of microwave-promoted Suzuki coupling reactions usin in situ Raman spectroscopy, Org. Lett, 8, 4589 591 (2006). 

G. Fevotte, In situ Raman spectroscopy for in-fine control of pharmaceutical crystallization and solids elaboration processes a review, Chem. Eng. Res. Des., 85, 906-920 (2007). 

T. Ono, J.H. ter Horst and P.J. Jansens, Quantitative measurement of the polymorphic transformation of L-glutamic acid using in-situ Raman spectroscopy, Cryst. Growth Des., 4, 465-469 (2004). 

C. Starbuck, A. Spartalis, L. Wai, et al., Process optimization of a complex pharmaceutical polymorphic system via in situ Raman spectroscopy, Cryst. Growth Des., 2(6), 515-522 (2002). 

Hugot-LeGoff, A. Pallotta, C. (1985) In situ Raman spectroscopy for the study of iron passivity in relation to solution composition. 

Terminal V=0 Bonds. - The terminal V=0 bonds can also be directly monitored with in situ Raman spectroscopy during the oxidation reactions, and... 

In situ Raman spectroscopy is being used to investigate corrosion products from zinc in a humid atmosphere and sodium chloride70 and from Type 304L stainless steel in aerated water at elevated temperatures and pressures.71 The changes in detected species over time helped identify possible corrosion mechanisms and the effect of different variables on corrosion rates and mechanisms. 

Ohtsuka, T. 8t Matsuda, M. In Situ Raman Spectroscopy for Corrosion Products of Zinc in Humidified Atmosphere in the Presence of Sodium Chloride Precipitate Corrosion 2003, 59, 407—113. 

Starbuck, C. Spartalis, A. Wai, L. etal Process Optimization of a Complex Pharmaceutical Polymorphic System Via In Situ Raman Spectroscopy Cryst. Growth Des. 2002, 2, 515-522. 

Zhou, G. Wang, J. Ge, Z. etal., Ensuring robust polymorph isolation using in-situ Raman spectroscopy Am. Pharm. Rev. 2002, 5, 74, 76-80. 

Wang, F. Wachter, J.A. Antosz, F.J. etal., An investigation of solvent-mediated polymorphic transformation of progesterone using in situ Raman spectroscopy Org. Process Res. Dev. 2000, 4, 391-395. 

Kuba S, Knozinger H. Time-resolved in situ Raman spectroscopy of working catalysts sulfated and tungstated zirconia. Journal of Raman Spectroscopy 2002, 33, 325-332. 

Spectroscopic Measurements. A Beckman Model 5230 spectrophotometer was used to record in situ UV-visible spectra of the PPy films, which were electrochemically deposited on the indium-tin oxide (ITO) coated glass (Delta Technologies). For Raman measurements a Spex Model 1403 double spectrometer, a DM IB Datamate, and a Houston Instrument DMP-40 digital plotter were employed. Details of the experimental setup for in situ Raman spectroscopy are described elsewhere (26). 

C(sp2)-H bonds during cathodic reduction and their dissociation during the oxidation step has been confirmed by in situ Raman spectroscopy [74],... 

Hutchings et al. (118) carried out in situ Raman spectroscopy experiments with VPA precursors as they were being converted into the active catalyst. They foimd that during the activation there is a structural disordering at 370 °C, which corresponds to the appearance of MA in the catalytic reaction product. The disordering was foimd to occur at a lower temperature (300 °C) when MA was added to the butane/air reaction mixture. This result demonstrated that the presence of the products is important in controlling the structural transformations and that a highly disordered structure can be important in selective butane oxidation. 

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