This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales.
2.
I was making up a chart at neutron reflectometry recently, noticing the variation between elements in coherent scattering, incoherent scattering, and absorption.
3.
Vanadium has a negligible absorption and coherent scattering cross section for neutrons and is hence nearly invisible in a powder diffraction experiment.
4.
The iridescence seen on a hummingbird's throat or a rainbow trout's flashing scales is one type of structural coloring, caused by so-called coherent scattering.
5.
This also means that in real space images, lattice planes edge-on are decorated not by diffuse scattering features but by contrast associated with coherent scattering.
6.
The long wavelength of the microwaves leads to effective point coherent scattering from the plasma in the laser focal volume, so phase matching is unimportant and scattering in the backward direction is strong.
7.
The image was taken from a region of the crystal which is thicker than the inelastic mean free path ( about 200 nanometres ), so that diffuse scattering features ( the Kikuchi lines ) would be strong in comparison to coherent scattering features ( diffraction spots ).
8.
These coherent scattering features include added diffraction ( responsible for bend contours in curved foils ), more electron penetration ( which gives rise to electron channeling patterns in scanning electron images of crystal surfaces ), and lattice fringe contrast ( which results in a dependence of lattice fringe intensity on beam orientation which is linked to specimen thickness ).
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