Interference microscopy technique

A major advantage of the recently developed interference microscopy technique [74, 75] is that in addition to allowing a direct measurement of sorption/desorption rates on the single crystal scale it provides, from the form of the transient concentration profiles, direct experimental evidence concerning the nature of the rate controlling resistances to mass ffansfer. Recent studies by this technique have shown that the influence of sffuctural defects and surface resistance to mass transfer are far more important than has been generally assumed [76-80]. For some systems it appears that sorption rates are controlled by surface resistance while in other cases the profiles suggest a combination of... 

While electron or ion beam techniques can only be applied under ultra-high vacuum, optical techniques have no specific requirements concerning sample environment and are generally easier to use. The surface information which can be obtained is, however, quite different and mostly does not contain direct chemical information. While with infra-red attenuated total reflection spectroscopy (IR-ATR) a deep surface area with a typical depth of some micrometers is investigated, other techniques like phase-measurement interference microscopy (PMIM) have, due to interference effects, a much better surface sensitivity. PMIM is a very quick technique for surface roughness and homogeneity inspection with subnanometer resolution. 

The direct visnalization of microstructure may be accomplished by various forms of microscopy. Recent refinements in microscopy techniques are epitomized by video-enhanced interference phase-contrast microscopy, which is emerging as a workhorse probe for colloidal suspensions and other microstructnred liqnids. 

Later, differential interference microscopy was developed, enabling the detection of difference in levels as sensitively as phase contrast microscopy, and, because this technique was easier to use, it came to be used in preference to the former techniques [6]. Differential interference microscopy is superior to phase contrast microscopy in the observation of vicinal or curved surfaces, which are impossible to observe under a phase contrast microscope because the contrast is too high. 

Bromination/EDXA (Chap. 4.4) has several disadvantages when compared to the other two techniques. Only relative lignin concentration can be determined directly by this method and a correction factor of 1.7 is required to obtain agreement between techniques (Saka et al. 1982, Donaldson and Ryan 1987). When bromination/EDXA and interference microscopy are used on matched samples, agreement is poor (Donaldson and Ryan 1987) as shown in Table 4.3.2. Not only is there poor quantitative agreement between the two methods, but EDXA data are also much more variable within each specimen. 

The accuracy of interference microscopy depends on the calibration standards used. For measurements in the secondary wall, these values are 1.604 for Nb and a range of values for Na depending on the specimen. The variation in Na arises presumably from variation in microfibril angle (Hermans 1946). The need to measure Na for each sample is one disadvantage of this technique that increases the amount of work necessary to perform the measurement. If Na is not measured for each sample, an error of 11% is introduced compared to the usual error of 2% (Donaldson 1985a). Na does not vary between earlywood... 

This is the most frequently used technique. In chapter 1 these systems were studied to obtain the surface or Interfacial tension from the shapes, see figs. 1.3 and 13. In fig. 5.19 they are redrawn with the contact angles indicated for two different cases of partial wetting. In principle, a can be measured by direct observation, obtained from a photograph, or by interference microscopy, which will be described later. Observations are usually carried out using a travelling tele-(mlcro)seope, as used in cathetometers, equipped with a goniometer eyepiece. So. 

Several studies report the use of replica techniques to assess abrasion in situ [45, 48], This methodology has also been successfully applied in vivo (see previous section). In this case, the wear is assessed using optical or interference microscopy. A drawback of this approach is that the production of replicas and positive copies inevitably provides a source of error and reduces the ability to measure small changes in tooth surface profile. 

A EXPERIMENTAL FIGURE 5-44 Live cells can be visualized by microscopy techniques that generate contrast by interference. These micrographs show live, cultured macrophage cells viewed by bright-field microscopy (/eft), phase-contrast microscopy middle), and differential interference contrast (DIC) microscopy righti. In a phase-contrast image, cells... 

One method is based on determining the refractive indexes of the two phases by interference microscopy. However this technique, which gives semi-quantative information, can be applied only if the particles of the dispersed phase are not too small (I, 2). We therefore prepared by anionic polymerization different copolymers of PS-PI containing a fluorescent group like styrene-9-phenyl-10-anthracene (see Structure 7 for structure of fluorescent copolymers). In such a PS-PI blend, the PI phase can be detected first by phase... 

The data obtained by this technique were confirmed by another technique using a PS-PI copolymer whose PI component was slightly chlorinated (1-2% total chlorine). Such a chlorinated copolymer is located in a PS-PI blend by an x-ray scanning microanalyzer (Castaing s Microsound). However this technique seems to have the same limitations as interference microscopy, especially for area A of Figure 7. 

In the first part of the chapter several methods used to observe morphology of polymer blends are presented. Various optical microscopic methods are reviewed, including such modem techniques as photon tunneling microscopy (PTM), scanning near-field optical microscopy (SNOM), phase measurement interference microscopy (PMIM), surface plasmon microscopy (SPM) and optical waveguide microscopy (OWM). Many of these methods have been developed to study surfaces and thin films. However, they can also be applied to polymer blend morphology. 

The design and application of a very promising novel technique for the measurement of sorbate transport in porous materials, viz. diffusion interference microscopy, is presented and pertinent results obtained by this technique are reported. 

Keywords Diffusion Co- and Counterdiffusion Adsorption IR techniques Interference microscopy... 

As schematically shown by Fig. 46a, ferrierite contains two mutually intersecting arrays of channels. In comparison with the strictly one-dimensional MOF crystals considered in the previous section, their analysis is additionally complicated by the existence of two rooflike parts on either side of the platelike main crystal body. It turned out, however, that these features did in no way complicate the method of analysis. Contrary to the MOFs, which required an additional activation step after each uptake experiment, methanol in ferrierite proved to be an ideal host-guest system, where one and the same crystal could alternately be subjected to adsorption and desorption without any perceptible change in the sorbate profiles. It were these special conditions under which interference microscopy could be developed to a technique of diffusion measurement in nanoporous materials of unprecedented power [63,65,70,71,88,89]. 

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