Raman normalization technique

The primary optical metiiods used in the past have been fluorescence and Raman spectroscopic techniques. The changes in tissue from a normal state to a cancerous state have been shown to alter the fluorescence and the Raman spectra. These methods have successfully differentiated normal tissues from Arose with breast, GYN, Colon and ADT cancers. 

This method has also been applied to medical problems related to disease diagnosis (e.g. arthero-sclerotic plaque) or optimization of medical treatment (e.g. bone implants). Flowever, medical applications of Raman spectroscopy do not necessarily require the combination with microscopy. Numerous studies have indicated that based on the analysis of Raman spectra by statistical methods it is possible to differentiate between normal and pathological tissues. Despite the substantial technical improvements, the intrinsically low sensitivity of Raman spectroscopy constitutes a limit for general applicability. Fluorescent samples may impose an additional constraint, which, however, can be overcome by near-infrared (1064 nm) Fourier-transform Raman spectroscopy and microscopy. In summary, it appears that for special medical applications Raman spectroscopic techniques may become a powerful diagnostic tool in clinical situations. 

Though normal Raman spectroscopy is a very selective technique for chemical analysis, there are some serious experimental disadvantages related to the sensitivity, large fluorescence interference, and lack of time resolution of the technique. These weaknesses have been addressed in the creation of new Raman-based techniques. The weak Raman signals due to inherently small Raman scattering efficiencies has been addressed by resonance Raman, surface-enhanced Raman and SPP-Raman techniques. Fourier transform-Raman spectroscopy and con-focal Raman microscopy address the disadvantage of... 

Raman scattering is normally of such very low intensity that gas phase Raman spectroscopy is one of the more difficult techniques. This is particularly the case for vibration-rotation Raman spectroscopy since scattering involving vibrational transitions is much weaker than that involving rotational transitions, which were described in Sections 5.3.3 and 5.3.5. For this reason we shall consider here only the more easily studied infrared vibration-rotation spectroscopy which must also be investigated in the gas phase (or in a supersonic jet, see Section 9.3.8). 

Normal mode analysis exists as one of the two main simulation techniques used to probe the large-scale internal dynamics of biological molecules. It has a direct connection to the experimental techniques of infrared and Raman spectroscopy, and the process of comparing these experimental results with the results of normal mode analysis continues. However, these experimental techniques are not yet able to access directly the lowest frequency modes of motion that are thought to relate to the functional motions in proteins or other large biological molecules. It is these modes, with frequencies of the order of 1 cm , that mainly concern this chapter. 

The first Raman and infrared studies on orthorhombic sulfur date back to the 1930s. The older literature has been reviewed before [78, 92-94]. Only after the normal coordinate treatment of the Sg molecule by Scott et al. [78] was it possible to improve the earlier assignments, especially of the lattice vibrations and crystal components of the intramolecular vibrations. In addition, two technical achievements stimulated the efforts in vibrational spectroscopy since late 1960s the invention of the laser as an intense monochromatic light source for Raman spectroscopy and the development of Fourier transform interferometry in infrared spectroscopy. Both techniques allowed to record vibrational spectra of higher resolution and to detect bands of lower intensity. 

Under Lespieau s directorship, the Ecole Normale laboratory was open to students in physics and mineralogy as well as chemistry.33 The primary research program was the synthesis and study of nonsaturated organic compounds, along with the application to hydrocarbons of physical methods like Raoulf s techniques. With his former student, Maurice Bourguel, Lespieau was one of the first people in France to apply Raman spectroscopy to organic analysis.34... 

Bauer et al. describe the use of a noncontact probe coupled by fiber optics to an FT-Raman system to measure the percentage of dry extractibles and styrene monomer in a styrene/butadiene latex emulsion polymerization reaction using PLS models [201]. Elizalde et al. have examined the use of Raman spectroscopy to monitor the emulsion polymerization of n-butyl acrylate with methyl methacrylate under starved, or low monomer [202], and with high soUds-content [203] conditions. In both cases, models could be built to predict multiple properties, including solids content, residual monomer, and cumulative copolymer composition. Another study compared reaction calorimetry and Raman spectroscopy for monitoring n-butyl acrylate/methyl methacrylate and for vinyl acetate/butyl acrylate, under conditions of normal and instantaneous conversion [204], Both techniques performed well for normal conversion conditions and for overall conversion estimate, but Raman spectroscopy was better at estimating free monomer concentration and instantaneous conversion rate. However, the authors also point out that in certain situations, alternative techniques such as calorimetry can be cheaper, faster, and often easier to maintain accurate models for than Raman spectroscopy, hi a subsequent article, Elizalde et al. found that updating calibration models after... 

The adsorption of alkyl and aryl isocyanides on Au film [26, 32, 33], powder [36, 37] and nanoparticles [39, 41, 42] has been studied using several different techniques IR methods (RAIR, ATR-IR, DRIFT), Raman methods (SERS), X-ray methods (NEXAFS), ellipsometry (OE, SWE) and contact angle measurements (ACA). The gold surface is not oxidized under normal conditions consequently, the experiments were performed in air at room temperature. The gold film was obtained by physical vapor deposition of 100-200 nm of gold on different substrates glass [28, 33], mica [33], silicon [25, 27, 31, 32], ZnSe crystal [26]. A... 

Both the Raman and the infrared spectrum yield a partial description of the internal vibrational motion of the molecule in terms of the normal vibrations of the constituent atoms. Neither type of spectrum alone gives a complete description of the pattern of molecular vibration, and, by analysis of the difference between the Raman and the infrared spectrum, additional information about the molecular structure can sometimes be inferred. Physical chemists have made extremely effective use of such comparisons in the elucidation of the finer structural details of small symmetrical molecules, such as methane and benzene. But the mathematical techniques of vibrational analysis are. not yet sufficiently developed to permit the extension of these differential studies to the Raman and infrared spectra of the more complex molecules that constitute the main body of both organic and inorganic chemistry. 

As its name implies, this technique offers very much greater sensitivity, by up to X ]06 compared with normal Raman spectroscopy. This occurs on roughened metal surfaces such as electrodes and cold-evaporated films. Unfortunately, the phenomenon at its best is highly selective, limited principally to the metals Cu, Ag, and Au. On these metals excellent spectra can be obtained (27, 28). Nevertheless, a few encouraging successes have been reported for the typical group Vlll metals, such as Ni, Pd and Pt, which are of principal catalytic interest (29). 

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