Polarized Raman spectroscopy

Process H2 concentration (%) CH4 concentration (%) Gas pressure (mbar) Substrate temp. ( O Bias voltage (V) Power (W) 

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The theory of orientation measurements by linearly polarized Raman spectroscopy has been developed in detail by Bower in 1972 [44]. The Raman intensity, I, is given by... 

G.S. Duesberg, I. Loa, M. Burghard, K. Syassen, and S. Roth, Polarized Raman spectroscopy on isolated single-wall carbon nanotubes. Phys. Rev. Lett. 85, 5436—5439 (2000). 

H.H. Gommans, J.W. Alldredge, H. Tashiro, J. Park, J. Magnuson, and A.G. Rinzler, Fibers of aligned single-walled carbon, nanotubes polarized Raman spectroscopy. J. Appl. Phys. 88, 2509—2514 (2000). 

R.R Paradkar, S.S. Sakhalkar, X. He and M.S. Ellison, On-line estimation of molecular orientation in polypropylene fibers using polarized Raman spectroscopy, Appl. Spectrosc., 55, 534-539 (2001). 

M. Tanaka and R.J. Young, Molecular orientation distributions in uniaxiaUy oriented poly(L-lactic acid) films determined by polarized Raman spectroscopy. Macromolecules, 39, 3312-3321 (2006). 

The self-organization of both thermotropic and lyotropic liquid crystals make these ordered fluids remarkable media for the dispersion and organization (alignment) of CNTs. This subject has been the focus of a recent excellent review by Scalia [231], theoretical work on anchoring at the liquid crystal/CNT interface by Popa-Nita and Kralj [458], and a number of earlier experimental reports on liquid crystal/CNT composites demonstrating that liquid crystal orientational order can be transferred to dispersed CNTs, which is commonly illustrated using polarized Raman spectroscopy [459 -62]. 

Key words dental, oral cavity, cancer, microorganisms, materials characterization, enamel, caries, polarized Raman spectroscopy, optical coherence tomography, clinic, fibre optics... 

Abbreviations PRS - polarized Raman spectroscopy, OCT - optical coherence tomography... 

Fig. 11.3. Representative Raman spectra of sound and carious enamel acquired using conventional non-polarized Raman spectroscopy...

To examine the concept of orientational changes of enamel rods, our followup studies report the use of polarized Raman spectroscopy (PRS) [44]. PRS... 

Paradkar, R.P. Sakhalkar, S.S. He, X. 8t Ellison, M.S. On-Line Estimation of Molecular Orientation in Polypropylene Fibers Using Polarized Raman Spectroscopy Appl. Spectrosc. 2001, 55, 534-539. 

Infrared dichroism is one of numerous methods used to characterize molecular orientation. The degree of anisotropy of the strained pol3rmers may also be accurately characterized by other techniques such as X-ray diffraction, birefringence, sonic modulus, polarized fluorescence and polarized Raman spectroscopy [2]. These techniques directly probe the orientational behavior of macromolecular chains at a molecular level, in contrast to the macroscopic information provided by mechanical measurements. 

Polarized Raman spectroscopy Polarized Raman spectroscopy is utilized to investigate molecular orientation and has special significance in the study of polymer systems. 

The in-plane orientations of both HOD film and Si(lOO) substrate were investigated by polarized Raman spectroscopy in Ref [263], and the results are shown in Figure 11.42. Define as the angle between the polarization of the laser light and... 

Polarized Raman spectroscopy of HOD films was also studied in Refs. [228, 351, 352]. The HOD film was grown by the three-step process under conditions listed in Table H.3 [351]. The angular dependence of polarized Raman spectroscopy was measured for both the 1332-cm line of the diamond film of 40-pm thickness and the 515-cm line of the Si(lOO) substrate. The results are shown in Figure 11.43. 

Raman spectroscopy has been used to probe interactions occurring in PAni nanotube [23-24] composites, the orientation of nanotube bundles within a matrix [25, 26], and the efficiency of load transfer from the host matrix to SWCNTs [27,28]. Unlike X-ray diffraction (XRD) methods [12], Raman spectroscopy can detect very low concentrations of SWCNTs in a polymer matrix [29,30]. The degree of orientation of aligned nanotubes can be estimated by polarized Raman spectroscopy due to the presence of a strong resonance Raman scattering effect [31,32]. Polarized Raman spectroscopy in combination with a mathematical model [33] has been employed to characterize the orientational order of nanotubes in polymers [34]. Using this model, the polarized Raman intensity of nanotubes is correlated with the orientation order parameters of SWCNTs in a utuaxially oriented system. An orientation distribution function can then be obtained. 

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