$critical angle for sound diffraction$

$critical angle for sound diffraction$

#CRITICAL ANGLE FOR SOUND DIFFRACTION SERIES#

There are only a few reports in the literature where both the oscillations in the X-ray reflectivity (XRR) at low diffraction angles and the Laue oscillations observed in the vicinity of a Bragg reflection are used to detect potential excess material.

$critical angle for sound diffraction$

The thickness obtained in this manner is often taken to be the total film thickness, which assumes that there is no additional thickness from amorphous or non-crystallographically aligned layers present above and/or below the diffracting crystal.

$critical angle for sound diffraction$

The most common quantitative analysis of Laue oscillations utilizes an equation derived from the Laue interference function to extract the total thickness of the crystalline phase, ,, ,, ,, ,. While it is true that Laue oscillations are a qualitative indicator of sample quality, the presence of Laue oscillations also provides an opportunity to gain significant structural information about films. The presence of Laue oscillations is frequently used as evidence of “the high crystallinity of samples”, “the uniformity of the film and smoothness of the interfaces”, or that “the out-of-plane order is high and coherent over the entire film thickness”. Generally, the presence of Laue oscillations are taken as confirmation that grown films are of high quality, homogenous, contain only the targeted compound, and have smooth and planar top and bottom interfaces, ,, ,, ,,. First predicted by Max von Laue, the Laue interference function relates the number of unit cells in the diffracting crystal to the distribution of diffracted intensity. It can be seen that this causes the wave to bend.Laue oscillations result from the incomplete destructive interference of a finite number of unit cells and occur when a sample consists of domains with the same number of unit cells across most of the area being probed. Therefore, when the wave encounters the interface between these two materials, the portion of the wave in the second material is moving faster than the portion of the wave in the first material.

#CRITICAL ANGLE FOR SOUND DIFFRACTION SERIES#

In the animation below, a series of plane waves are shown traveling in one material and entering a second material that has a higher acoustic velocity. The velocity of sound in each material is determined by the material properties (elastic modulus and density) for that material. The difference in speeds causes the wave to bend. Because of the angle, part of the wave enters the new medium first and changes speed. This change in angle of direction is called refraction. When sound changes mediums (enters a different material) at an angle other that 90 degrees, it is bent from its original direction. Sound waves travel outward in straight lines from their source until something interferes with their path. Remember that sound travels faster in some materials than others. Try this with multiple material pairs and observe what happens. Set the angle of Material 1 to 90 degrees. Set Materials 1 and 2 to different values.

$critical angle for sound diffraction$

Critical angle for sound diffraction