Optical microscopy, macroscopic

Microscopy is one of the most direct physical methods for determining surface roughness. The resolution can go from macroscopic to atomic size, depending on the technique. Thus the order of magnitude of the range of observation is the millimeter for optical microscopy, the micrometer for... 

There are two typical definitions of the induction time (ti) in CNT given by Frisch [16] and by Andres and M. Boudart [17]. x is an increasing function of N, t,(N). In previous studies, the special case N = N was usually focused on. As any critical nucleus can not be directly observed, Tj(N ) has been estimated from r (N) of macroscopic nuclei by optical microscopy by correcting the time necessary for growth from N to N. Therefore, x (N ) is named r (OM) in this work. It should be noted that there is no guarantee that the estimated Xi(N ) = r (OM) is correct, that is also an important unresolved problem. 

Fig. 20 (a) Stacked layers of parallel helices, with a 120° twist between adjacent layers, result in a sieve-like pattern with hexagonal symmetry, (b) A similar structure is obtained by inter-connected DNA strands and replicated into millimeter-sized crystals, as shown in the optical microscopy image in (c). Adapted with permission from [81]. (d) Design of a triangle from seven strands. The relative position of helices (1, 2, 3) at the vertices (a, b, c) is discussed in the text. Sticky ends mediate the aggregation of tiles into macroscopic rhombohedral crystals, shown in the optical microscopy image in (e). Adapted with permission from [82]... 

Optical microscopy can be used to assess the dispersion quality of the nanotubes during the different steps of the composite processing. Figure 12.4 shows a uniform distribution of particles on macroscopic and microscopic scales after adding an isopropyl suspension of MWNTs to a solution of natural rubber (NR). Considering the resolution limit of optical microscopy, we deduce the absence of aggregates larger than one micrometer. 

Optical microscopy is particularly useful for investigating various anisotropic features of polymeric systems. Polymers are intrinsically anisotropic objects and, when arranged in anisotropic structures such as crystalline and liquid crystalline phases, they display macroscopic optical anisotropy. These are investigated using a polarizing microscope, i.e., under crossed polarizers. 

Note that the letter is different in front and back. The other symmetry elements of the letter A are also indicated. The six basic point-symmetry elements (1, 2, 3,4, 6, and i) can describe the crystal symmetry as it is macroscopically recognizable by inspection, if needed, helped by optical microscopy. 

Thermal optical microscopy also finds extensive use in the analysis of optically active mesophases where the molecules can form macroscopic helical structures. For instance, the pitch length for helical phases can be determined by measuring the distances between the defect lines formed through the interaction of the helical structure and the surface of the preparation. The microscope can also be used as polarimeter to determine helical twist direction for homeotropically aligned helical mesophases. 

The macroscopic structure of matter can be assessed, for example, by optical microscopy and can then be linked to its microscopic origin through X-ray, neutron, or electron diffraction experiments and the various forms of electron and atomic-force microscopy. A factor of 10 -10 separates the atomic, nanometer scale from the macroscopic, micrometer scale. Macroscopic dynamic techniques ultimately linked to molecular motion are, for example, dynamic mechanical and dielectric analyses and calorimetry. In order to have direct access to the details of the underlying microscopic motion, one must, however, use computational methods. A realistic microscopic description of motion has recently become possible through accurate molecular dynamics simulations and will be described in this review. It will be shown that the basic large-ampHtude molecular motion exists on a picosecond time scale (1 ps = 10 s), a ffictor at... 

To show that the observed TGBL phase does not only possess a lamellar structure as proven with X-ray difraction, but that it also possesses a macroscop-ically hehcal structure, it was also investigated with polarized optical microscopy. A sample with the same concentration of IV-methylformamide as used in the X-ray diOiraction measurements was prepared and annealed between untreated glass plates to achieve a characteristic fingerprint texture in the N phase. Texture images of this... 

Banded spherulites, eg in PE (179,180), poly(vinylidene fluoride) (PVDF) (181), or polyhydroxyalkanoates (182), have also been studied in detail. The periodic bands detected in optical microscopy correspond typically to periodic corrugations along the radial direction of the spherulite. Particularly interesting is the case of PVDF (181). On the basis of a careful analysis it was found that the slopes of the observed multilayer terraces of lamellar crystals are retained in each half of a banded spherulite. This evidence confirmed the macroscopic selection of one-handedness in the formation of spiral terraces in each growth direction of the sheaf at the center of banded spherulites of PVDF (181). 

The NSLC samples were characterized using optical microscopy to probe the macroscopic alignment of the polymer network and scanning electron microscopy to probe the surfrce of the polymer network. 

Historically, a simple method of this macroscopic structural level characterization is connected with optical microscopy and etch figure analysis. The first and easiest step of single-crystal characterization is to observe the overall growth shape and macrodefects... 

Recent research has also addressed two issues. First, to what extent does the macroscopic measured draw ratio reflect the network draw ratio, and whether slippage occurs at a molecular level. Although curve matching attempts to resolve this problem it has also been instructive to invite more sophisticated molecular studies, for example by scanning near-field optical microscopy [97]. 

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