Raman spectroscopy system

Fig. 5.6. A block diagram of an optical coherence tomography/Raman spectroscopy system C, circulator RSOD, rapid scanning optical delay BP, 785 bandpass BSO, beam shaping optics DM1, dichroic mirror at 990 nm DM2, dichroic mirror at 800-950 nm LP, long pass at 808 nm GP, galvanometer pair BD, balanced detector BPF, electronic band-pass filter AI-AO DAQ, analog input-output data acquisition (reprinted with permission from [34]. Copyright 2008 Optical Society of America)...

Huang ZW, Zeng HS, Hamzavi I, McLean DI, Lui H. Rapid near-infrared Raman spectroscopy system for real-time in vivo skin measurements. Optics Letters 2001, 26, 1782-1784. 

Figure 15.5 Schematic of instrumental apparatus. The DT/MH-functionalized AgFON was surgically implanted into a rat with an optical window and integrated into a conventional laboratory Raman spectroscopy system. The Raman spectroscopy system consists of a Ti sapphire laser (Acx = 785 nm), band-pass filter, beam-steering optics, collection optics, and a long-pass filterto reject Raleigh scattered light. All of the optics fit on a 4 ft x 10 ft optical table.

Ogura A, Yamasaki K, Kosemura D, Tanaka S, Chiba 1, Shimidzu R (2006) UV-Raman spectroscopy system for local and global strain measurements in Si. Jpn J Appl Phys 45 3007... 

Confocal detection schemes enable Raman signal to be obtained from well-defined volumes within a thick sample [24-26]. Jongsma et al, [27] developed a confocal Raman spectroscopy system for noncontact scanning of ocular tissues up to 13 mm deep into the eye (Fig. 8). It was used in various in vitro and in vivo studies that addressed the (monitoring of changes in) hydration of the cornea [28] and the diffusion of topically applied pharmaceuticals through the cornea [29]. Care was taken to stay below the maximum permissible exposure of the retina as defined by the American National Standards Institute [30]. 

FHM Jongsma, RJ Erckens, JP Wicksted, NCJ Bauer, F Hendrikse, WF March, M Motamedi. Confocal Raman spectroscopy system for noncontact scanning of ocular tissues An in vitro study. Opt Eng 36 3193-3199, 1997. 

Table 1 Raman Spectroscopy Systems for the Instructional Laboratory... 

Surface-enhanced Raman spectroscopy (SERS) can be observed on almost any instructional Raman spectroscopy system, but the technique appears infrequently in the pedagogical literature. One impediment is the need to prepare colloidal silver [12] or another SERS-active surface before even simple experiments can be performed. Although surface preparations are not difficult, they do require more practice time than is available in the crowded curriculum. 

DA Fitzwater, KA Thomasson, RJ Glinski. A modular Raman spectroscopy system using a helium-neon laser that is also suited for emission spectrophotometry experiments. J Chem Ed 72(2) 187-189, 1995. 

Infrared and Raman spectroscopy each probe vibrational motion, but respond to a different manifestation of it. Infrared spectroscopy is sensitive to a change in the dipole moment as a function of the vibrational motion, whereas Raman spectroscopy probes the change in polarizability as the molecule undergoes vibrations. Resonance Raman spectroscopy also couples to excited electronic states, and can yield fiirtlier infomiation regarding the identity of the vibration. Raman and IR spectroscopy are often complementary, both in the type of systems tliat can be studied, as well as the infomiation obtained. 

Laser Raman diagnostic teclmiques offer remote, nonintnisive, nonperturbing measurements with high spatial and temporal resolution [158], This is particularly advantageous in the area of combustion chemistry. Physical probes for temperature and concentration measurements can be debatable in many combustion systems, such as furnaces, internal combustors etc., since they may disturb the medium or, even worse, not withstand the hostile enviromnents [159]. Laser Raman techniques are employed since two of the dominant molecules associated with air-fed combustion are O2 and N2. Flomonuclear diatomic molecules unable to have a nuclear coordinate-dependent dipole moment caimot be diagnosed by infrared spectroscopy. Other combustion species include CFl, CO2, FI2O and FI2 [160]. These molecules are probed by Raman spectroscopy to detenuine the temperature profile and species concentration m various combustion processes. 

Raman spectraof [INFRARED TECHNOLOGY AND RAMAN SPECTROSCOPY - RAMAN SPECTROSCOPY] (Voll4) -role in drug delivery pRUG DELIVERY SYSTEMS] (Vol 8)... 

A small but artistically interesting use of fluorspar is ia the productioa of vases, cups, and other ornamental objects popularly known as Blue John, after the Blue John Mine, Derbyshire, U.K. Optical quaUty fluorite, sometimes from natural crystals, but more often artificially grown, is important ia use as iafrared transmission wiadows and leases (70) and optical components of high energy laser systems (see Infrared and RAMAN spectroscopy Lasers) (71). 

Raman spectroscopy of graphite can be an experimental challenge, because the material is a strong blackbody absorber. Generally, low (1—10-mW) laser power is used to minimise heating, which causes the band positions to change. In addition, the expansion of the graphite causes the material to go out of the focus of the optical system, an effect which can be more pronounced in microprobe work. 

Biological Systems. Whereas Raman spectroscopy is an important tool of physical biochemistry, much of this elegant work is of scant interest to the industrial chemist. However, Raman spectroscopy has been used to locate cancerous cells in breast tissue (53) and find cataractous tissue in eye lenses (54), suggesting a role in industrial hygiene (qv). Similarly, the Raman spectra of bacteria are surprisingly characteristic (55) and practical apphcations are beginning to emerge. 

Biosensors (qv) and DNA probes ate relatively new to the field of diagnostic reagents. Additionally, a neat-infrared (nit) monitoring method (see Infrared TECHNOLOGY AND RAMAN SPECTROSCOPY), a teagenfless, noninvasive system, is under investigation. However, prospects for a nit detection method for glucose and other analytes ate uncertain. 

Infrared (in) spectrometers are gaining popularity as detectors for gas chromatographic systems, particularly because the Fourier transform iafrared (ftir) spectrometer allows spectra of the eluting stream to be gathered quickly. Gc/k data are valuable alone and as an adjunct to gc/ms experiments. Gc/k is a definitive tool for identification of isomers (see Infrared and raman spectroscopy). 

Pressure-induced phase transitions in the titanium dioxide system provide an understanding of crystal structure and mineral stability in planets interior and thus are of major geophysical interest. Moderate pressures transform either of the three stable polymorphs into the a-Pb02 (columbite)-type structure, while further pressure increase creates the monoclinic baddeleyite-type structure. Recent high-pressure studies indicate that columbite can be formed only within a limited range of pressures/temperatures, although it is a metastable phase that can be preserved unchanged for years after pressure release Combined Raman spectroscopy and X-ray diffraction studies 6-8,10 ave established that rutile transforms to columbite structure at 10 GPa, while anatase and brookite transform to columbite at approximately 4-5 GPa. 

Information exists about the use of measuring cells made entirely of diamond or graphite with or without embedded diamond windows. Diamond cells were used, for instance, by Toth and Gilpatrick [333] in the investigation of the Nb(IV) spectrum in a LiF - BeF2 molten system at 550°C. Windowless graphite cells for the IR spectroscopy of melts were developed by Veneraky, Khlebnikov and Deshko [334]. Diamond, and in some cases windowless sapphire or graphite micro-cells, were also applied for Raman spectroscopy measurements of molten fluorides. 

Until today the only available data obtained by direct sampling of a prototype battery system concerning mass flow of the complexing agents as well as the Br2 produced in both the aqueous and non-aqueous electrolyte phases have been gained by application of Raman spectroscopy [89, 90]. 

Film-forming chemical reactions and the chemical composition of the film formed on lithium in nonaqueous aprotic liquid electrolytes are reviewed by Dominey [7], SEI formation on carbon and graphite anodes in liquid electrolytes has been reviewed by Dahn et al. [8], In addition to the evolution of new systems, new techniques have recently been adapted to the study of the electrode surface and the chemical and physical properties of the SEI. The most important of these are X-ray photoelectron spectroscopy (XPS), SEM, X-ray diffraction (XRD), Raman spectroscopy, scanning tunneling microscopy (STM), energy-dispersive X-ray spectroscopy (EDS), FTIR, NMR, EPR, calorimetry, DSC, TGA, use of quartz-crystal microbalance (QCMB) and atomic force microscopy (AFM). 

The first successful application of the continuous wave (CW) He-Ne gas laser as a Raman excitation source by Kogelnik and Porto (14) was reported in 1963. Since that time, significant improvements in instrumentation have been continually achieved which have circumvented a great number of problems encountered with mercury lamp sources. The renaissance of Raman spectroscopy has also been due to improvements in the design of monochromators and photoelectric recording systems. 

A Summary of Adsorbate-Adsorbent Systems Investigated Using Laser Raman Spectroscopy... 

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