Interface angle

Interface angle which forms between crystal and melt... 

We find that the rotation rate affects both the "interface angle", i.e.- the angle between crystal and melt, cuid control of crs tal diameter, as shown in the following diagram, given as 6.4.7. on the next page. 

Note that we have defined "interface angle" as the angle between the growing crystal and the residual melt. Rate of pulling also ciffects the quality of the crystal as well as the actual number of intrinsic defects which may appear in the final crystal. In the upper left of 6.4.7., aflat-... 

Note that we have defined "interface angle" as the angle between the growing crystal and the residual melt. Rate of pulling also affects the... 

The interfaces between the ferrite and the metallic films can affect the head performance, since they represent two additional gaps. Based on purely geometrical considerations, these effects can be greatly reduced by changing the interface angles with respect to the gap. Fig. 6.34(c)... 

Figure 23 Illustration of Steno s law the constancy of interface angles (a) a regular hexagon (b) a distorted hexagon.

When light encounters a boundary between two transmissive mediums with differing index of refraction value, it may be reflected back into the first medium at the interface boundary, bent at a different trajectory (i.e refracted) as it passes into the second medium, or some combination of the two (see Figure 9.2). The actual result depends on the angle the light strikes the interface (angle of incidence) and the wavelength-dependent index of refraction values for the two materials. 

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. 

The external reflection of infrared radiation can be used to characterize the thickness and orientation of adsorbates on metal surfaces. Buontempo and Rice [153-155] have recently extended this technique to molecules at dielectric surfaces, including Langmuir monolayers at the air-water interface. Analysis of the dichroic ratio, the ratio of reflectivity parallel to the plane of incidence (p-polarization) to that perpendicular to it (.r-polarization) allows evaluation of the molecular orientation in terms of a tilt angle and rotation around the backbone [153]. An example of the p-polarized reflection spectrum for stearyl alcohol is shown in Fig. IV-13. Unfortunately, quantitative analysis of the experimental measurements of the antisymmetric CH2 stretch for heneicosanol [153,155] stearly alcohol [154] and tetracosanoic [156] monolayers is made difflcult by the scatter in the IR peak heights. 

Brewster angle microscopy takes advantage of the reflectivity behavior of light at an interface. This method relies on the fact that light passing from a material of lower refractive index, no into a medium of higher index i will have... 

In the context of the structural perturbations at fluid-solid interfaces, it is interesting to investigate the viscosity of thin liquid films. Eaily work on thin-film viscosity by Deijaguin and co-workers used a blow off technique to cause a liquid film to thin. This work showed elevated viscosities for some materials [98] and thin film viscosities lower than the bulk for others [99, 100]. Some controversial issues were raised particularly regarding surface roughness and contact angles in the experiments [101-103]. Entirely different types of data on clays caused Low [104] to conclude that the viscosity of interlayer water in clays is greater than that of bulk water. 

Optical second-harmonic generation (SHG) has recently emerged as a powerful surface probe [95, 96]. Second harmonic generation has long been used to produce frequency doublers from noncentrosymmetric crystals. As a surface probe, SHG can be caused by the break in symmetry at the interface between two centrosymmetric media. A high-powered pulsed laser is focused at an angle of incidence from 30 to 70° onto the sample at a power density of 10 to 10 W/cm. The harmonic is observed in reflection or transmission at twice the incident frequency with a photomultiplier tube. 

Here, fisAB denotes the angle as measured in liquid A, and the phases in parentheses have saturated the immediately preceding phase. A strictly rigorous nomenclature would be yet more complicated we simply assume that A and B are saturated by the solid and further take it for granted that the two phases at a particular interface are mutually saturated. mutual saturation effects are neglected, then the combination of Eqs. X-23 and X-21 gives... 

Ruch and Bartell [84], studying the aqueous decylamine-platinum system, combined direct estimates of the adsorption at the platinum-solution interface with contact angle data and the Young equation to determine a solid-vapor interfacial energy change of up to 40 ergs/cm due to decylamine adsorption. Healy (85) discusses an adsorption model for the contact angle in surfactant solutions and these aspects are discussed further in Ref. 86. 

Fowkes and Harkins reported that the contact angle of water on paraffin is 111° at 25°C. For a O.lAf solution of butylamine of surface tension 56.3 mJ/m, the contact angle was 92°. Calculate the film pressure of the butylamine absorbed at the paraffin-water interface. State any assumptions that are made. 

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