M-line spectroscopy

Sample d ( 30nm) profilometry d ( 20nm)m-line spectroscopy d(nm)... 

As predicted by Eq. 4, one would expect to see a poling-induced birefringence in the refractive index. In fact, this difference between the two refractive indices (ordinary index and extraordinary index n ) can be measured. Figure 3 shows the example of a poled DANS side-chain polymer, where the indices have been measured using m-line spectroscopy with a grating coupler. The diagram also reveals a wavelength dependence of the indices, an effect that will be further discussed in Section II.E. 

FIGURE 3 Ordinary (nj and extraordinary (n ) refractive indices of DANS side-chain polymer poled at 80 V / /xm (nominal poling field). The data were obtained by m-line spectroscopy with a grating coupler on a planar waveguide. 

Figure 17-3. The apparatusformode spectroscopy using prism coupling (a) m-line spectroscopy, where two prisms are used, for in-and out-coupling, respectively (b) dark-line spectroscopy, where a single prism is used for both functions.

Sometimes, especially when it may be necessary to check the homogeneity of films in the volume close to the surface, it is useful to combine m-line spectroscopy with another method, such as an Abeles modified method (Hacskaylo, 1964). As these two techniques may provide complementary information, a more accnrate and detailed characterization may be achieved (Pelli, 2002). 

Figure 19-1. Experimental setup used for luminescence measurements in waveguide configuration. The laser light is injected into the guide by prism coupling, as in the typical arrangement used for m-line spectroscopy (Slits (S) Grating (G) Lens (L) Mirror (M) Beam splitter (BS) Reference diode (D)).

B. Studies of Equilibria and Reactions.—N.m.r. spectroscopy is being increasingly employed to study the mode and course of reactions. Thus n.m.r. has been used to unravel the mechanism of the reaction of phosphorus trichloride and ammonium chloride to give phosphazenes, and to follow the kinetics of alcoholysis of phosphoramidites. Its use in the study of the interaction of nucleotides and enzymes has obtained valuable information on binding sites and conformations and work on the line-widths of the P resonance has enabled the calculation of dissociation rate-constants and activation energies to be performed. 

The conformations in solution of various acylated l,l-bis(acyl-amido)-l-deoxypentitols have been examined by p.m.r. spectroscopy.793 In line with general behavior observed78 with other acyclic-sugar derivatives, it was found that the arabino and lyxo derivatives adopt extended, zigzag conformations, whereas the ribo and xylo derivatives favor sickle conformations that result by rotation about one carbon-carbon bond of the backbone chain to alleviate a destabilizing 1,3-interaction of acyloxy substituents that would be present in the extended, zigzag conformation. 

Edwards, H.G.M. Raman Spectroscopy in the Characterization of Archaeological Materials. In Lewis, I.R. Edwards, H.G.M. (eds) Handbook of Raman Spectroscopy From the Research Laboratory to the Process Line 1st Edition Marcel Dekker, Inc. New York, 2001 pp. 1011-1044. 

The concentration of the sample in a particular solvent has little effect on chemical-shift values and, because of the inherently low sensitivity of 13C-n.m.r. spectroscopy, it is advantageous to use as concentrated solutions as possible when measuring these spectra. However, increased concentration, and consequently increased viscosity, causes line broadening due to decreased, spin-lattice relaxation-times (Tj values),18 and thus, poorer resolution. Certain solvents that tend to give viscous solutions (for example, Me2SO-d6) may also give decreased resolution. 

Carbon-13 N.M.R. Spectroscopy.—A study of the, 3C n.m.r. spectra of twenty-five hemiterpenoid quinoline alkaloids and related prenylquinolines, including C-, 0-, and A-prenyl-quinoline and -quinolone derivatives, hydroxyisopropyldihydro-furoquinolinones, hydroxydimethyldihydropyranoquinolinones, and furoquino-lines, has been carried out 6 only isolated examples were reported previously.7,8... 

The minor alkaloid aralionine B from the leaves of Araliorhamnus vaginata has been shown to possess structure (29).24 The structure elucidation followed the now conventional lines of extensive application of n.m.r. spectroscopy and mass... 

Parsons, M. L., and McElfresh, P. M. Flame Spectroscopy Atlas of Spectral Lines. New York IFI/Plenum, 1971. 

Fig. 8. Two-dimensional exchange spectroscopy (often called 2D-ELDOR) of the spin-labeled 3K-8 peptide with mixing time T = 296 nsec. Both the 2D surface and the contour map are shown. The peaks along the diagonal are related to the absorption spectrum of the spin label. The high-held M,= - line is weak because of experimental dead time artifacts. The cross-peaks, especially those between the outermost hyperfine lines, provide direct evidence of Heisenberg spin exchange. The cross-peak intensity can be used to determine the second-order rate constant for collisions between peptides.

Studied with variable-temperature C and H -N M R spectroscopy, and the line shape analysis led to activation energies of the rotations (ca. 50 and 20 kj mol for the two rotations), in good agreement with the predictions based on molecular mechanics calculations [557]. 

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