CHEM02200704003 Nilamadhab Pandhy - Homi Bhabha National ...

Chapter 3
Glancing incidence e is a scattering geometry i.e. a combination of Bragg’s condition with
the conditions for X-ray total external reflection from crystal surfaces [76,77]. The advantage of
small penetration depth and enhanced X-ray intensities ties at the surface makes glancing angle X-rays
suitable for non-destructive characterization of various material properties. The geometry for
Glancing Incidence X-ray Diffraction is shown in Fig. 2.5 [76].
Fig. 3.5: : Schematic of Glancing Incidence X-ray Diffraction [76].
The wave E 0 incidents on the surface at small angle 0 produces specularly reflected wave
E S . However, in order to diffraction to occur from the surface, the incident wave E 0 has to meet
some atomic planes perpendicular to the surface at a Bragg angle of B . This is usually carried out
by rotating the specimen about a normal to the surface, preserving the small angle 0 as shown in
Fig. 3.5. . Though, the diffracted wave will be directed inwards to the plane, the reciprocal lattice
vector being parallel to the surface, its specularly reflected counterpart E h appears, taking off the
crystal at small angle h . The wave E h can also be treated as Bragg’s diffraction of specularly
reflected wave E s , and E h contains the structural information of very thin layer surface. The