Like light, X-RAY also conducts the phenomena of Reflection. By which we can determine the quality, surface design, electron density, thickness of a polymer surface (both liquid and solid).
The basic idea behind the technique is
to reflect a beam of X-rays from a flat
surface and then measure the intensity of reflected X-rays in the specular
direction (reflected angle equal to incident angle).In 1954 Lyman G. Parrat first described the process of reflection by X-Ray. But in that time the more use of the process was not found.
PROCESS: The polymer surface was formed by spin coating method on hydrophilic silicon substrate.
Then the X-RAY falls upon polymer surface with different angle by the X-ray generate transducer. the X-RAY generator should be movable around the polymer surface. then a movable receptor will detect the higher intencity reflected X-ray with different angle around the polymer surface.
Then we have to make a plot intensity vs angle of incident ray.
Then we have to make a plot intensity vs angle of incident ray.
WAVE VECTOR, K=(2π/λ)sinθ where λ=wavelength of incident X-ray(almost 1.54Å)
θ=incident angle
By which we can find out wave vector and put this value to d=2π/Δk where Δk=difference of wave vector for two different angle and d= thickness of polymer surface.
Electron density of the surface, Ρelectron =(δ×2Ï€)/r0×λ2
nucleus radius r0=2.82×10-13cm.
Real componant of Refractive index δ=Θ(RAD)2/2
(WHERE Refractive index n=1-δ + iβ, β= imaginary componant)
Substituting the value of Θ(RAD) for two different angle of higher X ray intencity , we can get the value of δ.
by this value we can solve out the value of electron density of the surface and also can have the value of refractive index of the matter.
As the reflection phenomena of light gives us the different crucial characteristic of substance. X-ray reflectivity also offers us the different result of the substsnce.
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