Monochromaticity 582 INDEX

A much better way would be to use phase contrast, rather than attenuation contrast, since the phase change, due to changes in index of refraction, can be up to 1000 times larger than the change in amplitude. However, phase contrast techniques require the disposal of monochromatic X-ray sources, such as synchrotrons, combined with special optics, such as double crystal monochromatics and interferometers [2]. Recently [3] it has been shown that one can also obtain phase contrast by using a polychromatic X-ray source provided the source size and detector resolution are small enough to maintain sufficient spatial coherence. 

In ellipsometry monochromatic light such as from a He-Ne laser, is passed through a polarizer, rotated by passing through a compensator before it impinges on the interface to be studied [142]. The reflected beam will be elliptically polarized and is measured by a polarization analyzer. In null ellipsometry, the polarizer, compensator, and analyzer are rotated to produce maximum extinction. The phase shift between the parallel and perpendicular components A and the ratio of the amplitudes of these components, tan are related to the polarizer and analyzer angles p and a, respectively. The changes in A and when a film is present can be related in an implicit form to the complex index of refraction and thickness of the film. 

Additions to the PLM include monochromatic filters or a monochromator to obtain dispersion data (eg, the variation in refractive index with wavelength). By the middle of the twentieth century, ultraviolet and infrared radiation were used to increase the identification parameters. In 1995 the FTIR microscope gives a view of the sample and an infrared absorption pattern on selected 100-p.m areas (about 2—5-ng samples) (37). 

The deflection refractometer (Fig. 8.4), which measures the deflection of a beam of monochromatic light by a double prism in which the reference and sample cells are separated by a diagonal glass divide. When both cells contain solvent of the same composition, no deflection of the light beam occurs if, however, the composition of the column mobile phase is changed because of the presence of a solute, then the altered refractive index causes the beam to be deflected. The magnitude of this deflection is dependent on the concentration of the solute in the mobile phase. 

If measurements are made in thin oxide films (of thickness less than 5 nm), at highly polished Al, within a small acceptance angle (a < 5°), well-defined additional maxima and minima in excitation (PL) and emission (PL and EL) spectra appear.322 This structure has been explained as a result of interference between monochromatic electromagnetic waves passing directly through the oxide film and EM waves reflected from the Al surface. In a series of papers,318-320 this effect has been explored as a means for precise determination of anodic oxide film thickness (or growth rate), refractive index, porosity, mean range of electron avalanches, transport numbers, etc. 

The rectangular plates yield on immersion in oily liquids of known refractive index the values of /3 and y, but crushed fragments usually show values intermediate between a and in one direction. Observations were made in light of variable wave length, obtained by a monochromatic illuminator, at 20°. The dispersion relations were found to be as stated in Table II. 

Ronot Trioli, C. Trouillet, A. Veillas, C. Gagnaire, H., Monochromatic excitation of surface plasmon resonance in an optical fibre refractive index sensor, Sens. Actuators A 1996, 54, 589 593... 

A quantitative description does become possible, however, if the system under examination satisfies special conditions. These include diffuse, monochromatic illumination, homogeneous pigmentation, isotropic scattering in the coating, no difference in refractive index between vehicle and air, and a coating so thick that the substrate has no effect on the exiting radiation. This is the special case treated by the Kubelka-Munk theory. 

Figure 1. Schematic view of the one-dimensional layered structure. The vertical lines denote discontinuities of refractive index distribution. The monochromatic plane wave is incident in the y direction with the electric field amplitude The amplitudes of reflected and transmitted waves are ref and, respectively.

Starting from Maxwell s equations with the ansatz of monochromatic, z-propagating fields, E, H Qx i k- co t)), transversal and longitudinal components get decoupled if the refractive index distribution is z-independent. Two physically equivalently meaningful equations for the transversal electric and the transversal magnetic field. 

Christiansen effect analy chem Monochromatic transparency effect when finely powdered substances, such as glass or quartz, are immersed in a liquid having the same refractive index. kris-chan-san i fekt ... 

For a monochromatic wave of frequency oa in an inhomogeneous and isotropic medium of refraction index n r), the electromagnetic field satisfies Eq. (1) with k given by... 

You can see from Fig. 9.8 that a Laue diffraction pattern is much more complex than a diffraction pattern from monochromatic X rays. But modern software can index Laue patterns and thus allow accurate measurement of many diffraction intensities from a single brief pulse of X rays through a still crystal. If the crystal has high symmetry and is oriented properly, a full data set can in theory be collected in a single brief X-ray exposure. In practice, this approach usually does not provide sufficiently accurate intensities because the data lack the redundancy necessary for high accuracy. Multiple exposures at multiple orientations are the rule. 

When a monochromatic, coherent light is incident into a dilute macromolecule solution, if solvent molecules and macromolecules have different refractive index, the incident light is scattered by each illuminated macromolecule to all directions [9, 10]. The scattered light waves from different macromolecules mutually interfere, or combine, at a distant, fast photomultiplier tube detector and produce a net scattering intensity I(t) or photon counts n(t) which is not uniform on the detection plane. If all macromolecules are stationary, the scattered light intensity at each direction would be a constant, i.e. independent of time. 

A linear birefringence involves the occurrence of an anisotropy between the components of the refractive index associated with linearly polarized monochromatic light whose polarization vector is directed along two perpendicular optical axes. In the examples discussed here the principal optical axis lies parallel to an external applied field, and... 

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