An Introduction to Neutron Scattering - Spallation Neutron Source

What do the Amplitudes a R and a T Look Like?
• For reflection from a flat substrate, both a R and a T are complex when k 0 < 4πρ
I.e. below the critical edge. For a I = 1, we find:
1
0.5
-0.5
-1
0.005 0.01 0.015 0.02 0.025
Real (red) & imaginary (green) parts of a R
plotted against k 0 . The modulus of a R is
plotted in blue. The critical edge is at
k 0 ~ 0.009 A -1 . Note that the reflected wave is
completely out of phase with the incident wave
at k 0 = 0
2
1.5
1
0.5
-0.5
-1
0.005 0.01 0.015 0.02 0.025
Real (red) and imaginary (green) parts
of a T . The modulus of a T is plotted in
blue. Note that a T tends to unity at
large values of k 0 as one would expect