PHYS01200804001 Sohrab Abbas - Homi Bhabha National Institute

Fig.28 Theoretical curves for Si {111} Bragg reflection and prism diffraction of 5.26 Å neutrons
with A=172 o and θ S =50.1 o as a function of the incidence angle.
scale gets compressed by the same factor relative to θ (cf. Eq.(64)). The dependence of the
diffracted intensity on the exit angle thus becomes (cf. intensity curves in Figs.29-31)
I
H
B S B S
H
B S B S
2
sin sin(A ) sin( )
. (65)
sin( )sin(A ) sin( )
On either side of the total reflectivity domain, θ H decreases on increasing y for all apex angles (cf.
Eq.(63)), but for apex angles greater than a crossover value A x , θ H (y =1) becomes greater than
θ H (y=−1) where
2
1 2sin
B
A
x
tan
tan
S . (66)
sin2S
64