Raman spectroscopy, in study

Raman spectra of pyrid-4-one, 353 2-thiophenealdehyde, 13 Raman spectroscopy, in study of tautomerism, 338 Reductones, structure of, 363 Refractive index, as method to study tautomerism, 337 Riedel synthesis, 300 Rutaecarpine, 301, 304... 

This review will endeavor to outline some of the advantages of Raman Spectroscopy and so stimulate interest among workers in the field of surface chemistry to utilize Raman Spectroscopy in the study of surface phenomena. Up to the present time, most of the work has been directed to adsorption on oxide surfaces such as silicas and aluminas. An examination of the spectrum of a molecule adsorbed on such a surface may reveal information as to whether the molecule is physically or chemically adsorbed and whether the adsorption site is a Lewis acid site (an electron deficient site which can accept electrons from the adsorbate molecule) or a Bronsted acid site (a site which can donate a proton to an adsorbate molecule). A specific example of a surface having both Lewis and Bronsted acid sites is provided by silica-aluminas which are used as cracking catalysts. 

Dong J, Zha S, and Liu M. Study of sulfur-nickel interaction using Raman spectroscopy. In Singhal SC, Mizusaki J, editors. Proceedings of the Ninth International Symposium on Solid Oxide Fuel Cells (SOFC-IX), Pennington, NJ The Electrochemical Society, 2005 2005(07) 1284-1293. 

The question as to the best formulation of structures and species in some binary fluoride systems was the subject of extensive experimental investigations, involving infrared and Raman spectroscopy in the molten state and in solutions as well as NMR spectroscopy and conductometric and cryoscopic measurements. Some crystal structure studies have also been published. The systems of SeF4 with BF3, SbF5, AsF5, NbF5, and TaFs have been studied recently. 

Recent studies on PEO-PPO, PEO-PBO di- and triblock copolymers include the works of Bahadur et al. [121], who examined the role of various additives on the micellization behavior, of Guo et al. [122], who used FT-Raman spectroscopy to study the hydration and conformation as a function of temperature, of Booth and coworkers [ 123], who were mainly interested in PEO-PBO block copolymers with long PEO sequences, and of Hamley et al., who used in situ AFM measurements in water to characterize the morphology of PEO-PPO micelles [56,57]. 

Further details of the theory and application of Raman spectroscopy in polymer studies can be found elsewhere (1. 9). However, vibrational frequencies of functional groups in polymers can be characterized from the spacing of the Raman lines and thus information complementary to IR absorption spectroscopy can be obtained. In addition, since visible radiation is used the technique can be applied to aqueous media in contrast to IR spectroscopy, allowing studies of synthetic polyelectrolytes and biopolymers to be undertaken. Conformation and crystallinity of polymers have also been shown to influence the Raman spectra Q.) while the possibility of studying scattering from small sample volumes in the focussed laser beam (-100 pm diameter) can provide information on localized changes in chemical structure. 

L.E. O Brien, P Timmins, A.C. Williams and P. York, Use of in situ FT-Raman spectroscopy to study the kinetics of the transformation of carbamazepine polymorphs, J. Pharm. Biomed. Anal., 36, 335-340 (2004). 

In the case of NOS 12, different kinetics were observed at 436 nm. In cyclohexane, there was a rapid rise, with a lifetime of 6.6 psec followed by a decay with a 100-psec lifetime. In 1-butanol, there was a rapid rise (lifetime=4.3 psec), a decay (43-psec lifetime), and a second longer decay within a 1.4-nsec lifetime. These findings were confirmed by picosecond time-resolved resonance Raman spectroscopy. In these Raman studies in cyclohexane, a single rate constant was observed, whereas in 1-butanol, three spectral components grew with different time constants. The data were said to be consistent with the photo-formation of two or three isomers trans about the central methine bond however, other transient species could be responsible for the observed kinetics because the absorption envelope obviously shifts and this would affect the resonance Raman bands. 

In the infrared region, and possibly also by Raman spectroscopy, more studies should be made of catalysts and catalytic reactions carried out in situ. By use of conventional transmission infrared techniques, it is also... 

McNicol et al. (49) used luminescence and Raman spectroscopy to study structural and chemical aspects of gel growth of A and faujasite-type crystals. Their results are consistent with a solid-phase transformation of the solid amorphous network into zeolite crystals. Beard (50) used infrared spectroscopy to determine the size and structure of silicate species in solution in relationship to zeolite crystallization. 

A number of structures in solution, of ammine and related complexes, have been determined by X-ray diffraction techniques, supported by the use of Raman spectroscopy. A study on... 

The careful study of Zn-Cl stretching frequencies by Raman spectroscopy in aqueous solutions of zinc chloride in hydrochloric acid solutions has allowed the quantitative study of [ZnCLj2- formation.977... 

Jonas and co-workers (68) used Raman spectroscopy to study the naphthalene-C02 system under high pressure. The experimental results (a blue shift of the C-H stretching and C-H out-of-plane bending modes) and model calculations presented indicate that quadrupole-quadrupole coupling is significant in this system. The preferred orientation of the 0=C=0 and naphthalene were determined to be face-to-face. 

In a different application of Raman spectroscopy to studies of zeolites, Cooney and Tsai (6) have investigated the adsorption of bromine on alkali exchanged zeolites X, NaY and NaA, and the... 

The subsequent reaction of bromine treated NaX and CsX with benzene revealed two types of behavior (35). At saturation Br2 coverage surface donor complexes were formed on sites III and II, whereas at less than Br2 saturation (only site II occupied) benzene reacted rapidly to form addition products containing carbon-bromine bonds. The unique ability to use Raman spectroscopy in general for obtaining low frequency spectral data in studies of in situ catalytic process was discussed by the authors. 

A major advantage of Raman spectroscopy in the chemical characterization of pollen is its applicability in situ. The pollen grains in this study were investigated without prior purification or extraction procedures, which has been the case in most other investigations on pollen composition so far [45, 46, 57, 58]. Using Raman microspectroscopy on sections of snap-frozen samples, the chemical composition and very likely also their ultrastructure remain unaltered, and the co-localization of individual components could be studied in the context of pollen micromorphology, simultaneously in very short... 

A series of advances over the past decade have made CRS microscopy a highly sensitive tool for label-free imaging and vibrational microspectroscopy that is capable of real-time, non-perturbative studies of complex biological samples based on molecular Raman spectroscopy. In particular, biomedical applications where fluorescent labeling of small molecules represents a severe pertur-... 

Many technical problems must be solved to enable routine use of Raman spectroscopy as an in vivo clinical tool. The employment of Raman spectroscopy in situ for the study of most tissues necessitates the use of fibre optics to deliver and return the signal from the tissue site. There have been a number of fibre probe designs considered and this is an active area of research [57-60, 10]. Clinical applications to date include GI tract [61], urology [62], lung [63], stomach [64] and cervix [65]. 

Though especially the cultural parameters of the studied cells have a huge impact on their signature variability it seems that - a decent Raman signature library provided - the majority of cultivation differences can be accommodated and thus no extreme standardization of culturing conditions is required for identification via this method. But for the sake of taxonomic resolution care has to be taken in finding appropriate culturing conditions to affect the implementation possibilities of Raman spectroscopy in microbial analysis positively [43]. 

In most cases, the two latter processes have been studied individually by fast techniques (flash photolysis, transient spectra measurements, Raman spectroscopy) in nano-, pico-, and femtosecond time scales as processes accompanying photophysical deactivation steps [64-66]. In Table 3 the data for such individual steps are reported. The data can be summarized as follows ... 

EPR, FTIR, RAMAN, UV-VISIBLE ABSORPTION, AND FLUORESCENCE SPECTROSCOPIES IN STUDIES OF NOM... 

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