Raman spectroscopic measurements

S.S. Cherukupalli, S.E. Gottlieb and A.A. Ogale, Real-time Raman spectroscopic measurement of crystallization kinetics and its effect on the morphology and properties of polyolefin blown films, J. Appl. Polym. Sci., 98, 1740-1747 (2005). 

S. Romero-Torres, J.D. Perez-Ramos, K.R. Morris and E.R. Grant, Raman spectroscopic measurement of tablet-to-tablet coating variability, J. Pharm. Biomed. Anal., 38, 270-274 (2005). 

The first subsurface bone tissue Raman spectroscopic measurements were performed using picosecond time-resolved Raman spectroscopy on excised equine cortical bone [56, 57], In these experiments it was shown that a polystyrene backing could be detected through 0.3 mm of bone. The same picosecond technology was used to perform the first transcutaneous Raman spectroscopic measurements of bone tissue [58]. In this study, the cortical bone mineral/matrix ratios of excised limbs of wild type and transgenic (oim/oim) mice were compared and the differences demonstrated. 

Transcutaneous Raman spectroscopic measurements using spatially offset optical fibers were reported less than a year later [59, 60]. The test systems were chicken tibiae and the humeri of human cadavers. The use of cadaveric and ex vivo specimens allowed validation of the measurements by comparison to exposed bone tissue. In these measurements a depth of 3-4 mm below the skin was reached. In vivo measurements began with a report of the Raman spectrum of a phalange of a human volunteer [61]. The periosteal surface was probably 1-2 mm below the skin and the mineral phosphate Vi was accurately reproduced, although incomplete separation of mineral and matrix spectra introduced errors in other bands. 

Another measure of solvent softness proposed is based on Raman spectroscopic measurements. It is the wavenumber shift Av of the Raman band for the symmetrical stretching of Br-Hg-Br in the solvent relative to that of gaseous mercury bromide (Persson 1986). A solvent softness scale, called Ds = [A (Hg-Br)/cm-J] has accordingly been established. An extension of this scale to further solvents is difficult in those cases where the solubility of mercury bromide is insufficient for the ca. 0.2 mol dm-3 required for the Raman spectral measurements. 

Lambert et al. have explored the use of Raman spectroscopic measurements of glucose present in the aqueous humor of the eye.20,21,31 This is undoubtedly an excellent portal for optical measurements with potential advantages such as easy access and less complex fluid composition. In spite of these advantages, a spectroscopic measurement in the eye carries the risk of injury if the probing light is too intense. Therefore, dosimetry and a foolproof light delivery method are important concerns for in vivo human studies. 

Munro CH, Pajcini V, Asher SA. Dielectric stack filters for ex situ and in situ UV optical-fiber probe Raman spectroscopic measurements. Applied Spectroscopy 1997, 51, 1722-1729. 

The opposed anvil cell consists of two optical anvils and a gasket, located between the parallel faces of the two opposing anvils. Samples are placed in the hole of the gasket and are pressurized when the opposed anvils are pushed towards each other. The most common material for anvils is diamond. For mid and far infrared spectra, type Ila diamonds are used, while low-fluorescent type la diamonds are used for Raman spectroscopic measurements [5]. We have also devised a glass anvil cell for Raman spectroscopic measurements [6], and a calcium fluoride anvil cell for infrared spectroscopic measurements [7] with attainable working pressures of 13 and 6 kbar, respectively. Diagrams, for the interested reader, of the window and opposed anvil cells can be found in reference 1. 

In view of the small sample size, the optical aperture used for pressure tuning vibrational spectroscopic measurements is also very small. This does not create serious problems for high pressure Raman spectroscopic measurements since the laser beam can be focused to 30-40 pm. Thus, the optical system employed in a standard Raman scattering experiment can be used and no special optical interface is required for the pressure tuning Raman spectroscopic measurements. 

For the Pb6(OH)g4+ solution the changed Pb-Pb peak shape at 3.85 A and two additional Pb-Pb peaks at, 6.4 and 7.1 A, indicate a more complex structure, which cannot be unambiguously derived from the limited information in the RDF. Crystals can be prepared, however, which contain discrete Pb60(0H)64+ units with the structure shown in Fig. 30 (227). Theoretical peaks calculated for the Pb framework in this structure are in complete agreement with the peaks in the RDFs (Fig. 30), which proves that the structure of the complexes are the same in solution and in crystals. Raman spectroscopic measurements are consistent with this interpretation. 

For a further discussion of the experimental limitations attendant to both attenuation and Raman-spectroscopic measurements, see Gandhi, O.P. Athey, T.W. Illinger,... 

Raman spectroscopic measurement was also used to explain the improved thermal stability of nontreated (NoM-C) and silylated cotton fibers (Sil-C).20 In the region 3200-3500 cm-1, peaks become more intense and narrower, demonstrating an apparent increase in the -OH group concentration in the ordered phase and an increase in the crystallinity. This phenomenon was explained by the fact that the silylation reaction cannot take place in the crystalline phase. The increase in crystallinity is the result of easier segmental motion, which is facilitated by the reduction of secondary chemical bonds in the amorphous phase. These structural changes explain the higher thermal stability, since the OH groups in the amorphous phase are more sensitive to thermal dehydration. 

X-ray and time-of-flight (TOF) neutron diffraction and Raman spectroscopic measurements have been carried out at 25°C on concentrated aqueous sulfuric acid solutions, (H2S04),(H20),, x = 0, 0.25, 0.5, 0.75 and 0.86, in order to investigate the hydrogen-bonded intermolecular stmcture in the solutions. The intramolecular parameters for regular tetrahedral SO4 unit were determined from the least squares fit to observed X-ray and neutron interference terms in the range of Q S 8. The nearest neighbor... 

The most extensive research results concern the hydride electrolyte system 2 [13-16, 68, 78, 82, 92, 93, 102, 209]. With the help of Raman spectroscopic measurements, the chemical constituents of the electrolyte were determined and the electrode reactions examined with chronoamperometric methods [82]. The catalytic role of hydride and the role of neutral and ionic aluminum components were thus detected. The dependence of the polarization parameters on the electrolyte composition shows a marked maximum from which the bath composition with the highest current distribution can be determined. The influence of the temperature and the composition on the electrode process kinetics was studied by Badawy et al. [13-16]. The results of Eckert et al. [68] show a dependence of the activation energy on the electrolyte composition of the hydride baths. The first electrochemical investigation results with respect to type 3 aluminum alkyl electrolyte were obtained by Kautek et al. [100, 101] and Tabataba-Vakili [186, 187, 133]. 

This review article is concerned with the structure, bonding, and dynamic processes of water molecules in crystalline solid hydrates. The most important experimental techniques in this field are structural analyses by both X-ray and neutron diffraction as well as infrared and Raman spectroscopic measurements. However, nuclear magnetic resonance, inelastic and quasi elastic neutron scattering, and certain less frequently used techniques, such as nuclear quadrupole resonance, electron paramagnetic resonance, and conductivity and permittivity measurements, are also relevant to solid hydrate research. 

Relatively few structural studies of radialenes have been carried out, and most of these are X-ray crystallographic studies. The first structure study of a radialene was, however, a gas electron diffraction study of 3 that appeared in 1968. The molecule was found to be planar with Dsh symmetry, in agreement with information from IR and Raman spectroscopic measurements. To the best of our knowledge only two structures of substituted [3]radialene have been reported since then. In both molecules all six hydrogens are equally substituted in one case with methyl groups (7) and in the other with trimethylsilylethynyl groups(8) see Figure 10. In hexamethyl[3]radialene (7) the... 

The more recent investigations based mainly on Raman spectroscopic measurements by Gilbert et al. (1976, 1995) indicate that anions with bridging Al-O-Al bonds are present, and have most probably the following structure... 

The formation of aqueous selenium(IV)-fluoride complexes in solutions of high HF(aq) concentration was detected by Milne [87M1L]. The study was based on Raman spectroscopic measurements and showed, at 28 M HF, the presence of new bands in addition to those of H2Se03(aq). The bands were interpreted as originating from a species HSe02F(aq). At even higher HF concentrations, > 50 M, additional Raman bands appeared and these were claimed to be due to a species SeOF2(aq). No attempts were made to elucidate thermodynamic information from the measurements. 

The formation of aqueous selenium(IV)-chloride complexes in solutions of high hydrochloric acid concentration has been studied by Milne and LaHaie [79M1L/HA1] and by Milne [87MIL]. The studies are based on Raman spectroscopic measurements and, in [79MIL/HAI], the occurrence of bands at 152, 265, and 336 cm were interpreted as originating from a species SeOCl2(aq). The intensities of these bands were significant at HCl concentrations of 7 M and above, and were used to deduce an equilibrium constant for the reaction... 

In solutions containing high HBr concentrations and Se(IV), elemental Se(cr) can be dissolved. Milne [89MIL] studied these reactions at 4.8 and 8.72 M HBr (293 K) by gravimetric and Raman spectroscopic measurements. 

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