Specular reflection of matter waves from a rough mirror
  We have made a high resolution study of the specularity of the atomic reflection from an evanescent wave mirror using velocity selective Raman transitions. We have observed a double structure in the velocity distribution after reflection: a peak consistent with specular reflection and a diffuse reflection pedestal, whose contribution decreases rapidly with increasing detuning. The diffuse reflection is due to two distinct effects: spontaneous emission in the evanescent wave and a roughness in the evanescent wave potential whose amplitude is smaller than the de Broglie wavelength of the reflected atoms. 
V. Savalli, D. Stevens, J. Esteve, P. D. Featonby, V. Josse, N.   Westbrook. C.I. Westbrook, A. Aspect