Glancing Angle X-ray Diffraction (GAXRD) Technique

Penetration Depth
• Penetration depth defined as the length at which the field
has fallen by a factor e-1 and can be expressed as
1
l ≡
Im k 'z 1
=
1
2 2
k ( cos α −ε'/
ε)
λ
≅
2 2
2Π
α −α
1
2
(7)
( c )
• However this term does not include absorption effects. On
including absorption effect, equation (7) is modified as
where
{
λ
2 2 2 2 2 2
l = ⎡ ( α − α ) + 4β + α −α
⎤ 2
C C
4Π
⎢⎣ ⎥⎦
Penetration Depth
µλ
β =
4Π
}12 −
(8)
µ is the linear mass absorption coefficient
λ is the the wavelength of the x-rays
• In the range of α=0 and when no absorption occurs equation
(8) is expressed as
λ
l =
4Πα C
• For α> α C; the depth penetration depth is determined mainly
by the photo absorption of the medium and is expressed as
⎛sinα ⎞
l ≅ ⎜
µ
⎟
⎝ ⎠
(9)
11
12