Line shape, 66 high resolution

Detection of Via recoils Via recoils ERDA Direct Direct Via line shapes High resolution... 

Fig. I. High-resolution electron micrographs of graphitic particles (a) as obtained from the electric arc-deposit, they display a well-defined faceted structure and a large inner hollow space, (b) the same particles after being subjected to intense electron irradiation (note the remarkable spherical shape and the disappearance of the central empty space) dark lines represent graphitic layers.

Another difficulty with the infrared method is that of determining the band center with sufficient accuracy in the presence of the fine structure or band envelopes due to the overall rotation. Even when high resolution equipment is used so that the separate rotation lines are resolved, it is by no means always a simple problem to identify these lines with certainty so that the band center can be unambiguously determined. The final difficulty is one common to almost all methods and that is the effect of the shape of the potential barrier. The infrared method has the advantage that it is applicable to many molecules for which some of the other methods are not suitable. However, in some of these cases especially, barrier shapes are likely to be more complicated than the simple cosine form usually assumed, and, when this complication occurs, there is a corresponding uncertainty in the height of the potential barrier as determined from the infrared torsional frequencies. In especially favorable cases, it may be possible to observe so-called hot bands i.e., v = 1 to v = 2, 2 to 3, etc. This would add information about the shape of the barrier. 

Figure 6.7. High-resolution ARUPS spectta measured at kp (hco = 21.2 eV) above (70 K) and below (30 K) the Peierls transition. The solid line spectrum corresponds to Ep, as determined for a silver film. Note that the spectrum follows the shape given by Eq. (1.27). Reprinted with permission from F. Zwick, D. Jerome, G. Margaritondo, M. Onellion, J. Voit and M. Grioni, Physical Review Letters, 81, 2974 (1998). Copyright (1998) by the American Physical Society.

Fig. 14. Plot of line shape change versus rate of exchange of protons between environments A and B. The intensities of the various line functions are not comparable. Reproduced by permission from "High-Resolution Nuclear Magnetic Resonance, by Pople, Schneider, and Bernstein. McGraw-Hill, New York, 1959.

Some swollen crosslinked polymer gels, such as styrene-divinylbenzene copolymers, exhibit high resolution spectra with so-called super-Lorentzian (SL) line shapes... 

Fig. 11. High-resolution 29Si MAS NMR spectra of synthetic zeolites Na-X and Na-Y at 79.80 MHz (58). Experimental spectra are given in the left-hand columns Si(nAl) signals are identified by the n above the peaks. Computer-simulated spectra based on Gaussian peak shapes and corresponding with each experimental spectrum are given in the right-hand columns. Individual deconvoluted peaks are drawn in dotted lines.

The most time consuming parts of the forward model are the calculation of the absorption coefficients and the calculation of the radiative transfer. A spectral resolution of Av = 0.0005 cm 1 is considered necessary in order to resolve the shape of Doppler-broadened lines. To avoid repeated line-shape and radiative transfer calculations at this high resolution, two optimizations have been implemented ... 

On the other hand, in the solid-state high resolution 13C NMR, elementary line shape of each phase could be plausibly determined using magnetic relaxation phenomenon generally for crystalline polymers. When the amorphous phase is in a glassy state, such as isotactic or syndiotactic polypropylene at room temperature, the determination of the elementary line shapes of the amorphous and crystalline-amorphous interphases was not so easy because of the very broad line width of both the elementary line shapes. However, the line-decomposition analysis could plausibly be carried out referring to that at higher temperatures where the amorphous phase is in the rubbery state. Thus, the component analysis of the spectrum could be performed and the information about each phase structure such as the mass fraction, molecular conformation and mobility could be obtained for various polymers, whose character differs widely. 

Nanotubes represent the typical nano-objects and this presentation would not be representative without at least one example. The high resolution image on the left-hand side of Figure 5 represents a nanotube, the detailed composition of which cannot be deduced from the image or any technique other than EELS. By performing line scans, it was possible to quantify all the detected elements (B, C, N) as a function of the probe position. From the atomic ratios and the shape of the atomic distribution, Suenaga et a . [16] demonstrated that this particular nanotube was made of a succession of 3 carbon layers, 6 boron nitride layers and finally 5 carbon layers. 

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