Thin-Film Interference in Reflected X-rays

Why X-rays reflecting off both a film's top surface and its buried substrate interface interfere with each other, producing oscillations in reflected intensity that encode the film's own thickness.

References

• Sinha, S.K., Sirota, E.B., Garoff, S., Stanley, H.B. "X-Ray and Neutron Scattering." Physical Review B 38, no. 4 (1988): 2297–2311.