Photoelectron diffraction was used to get polar plots of the low-energy photoemission intensities from AlAs monolayer buried 2, 3 and 4 GaAs monolayers below the GaAs(0 0 1)- c (4×4) reconstructed surface. Unexpected differences in polar plots of the layer-resolved, synchrotron radiation excited photoelectron emission from even and odd AlAs monolayers were observed experimentally and obtained theoretically. This 26 eV kinetic energy photoelectron emission is accompanied by electron attenuation anisotropy and a non-exponential intensity decay in the near-surface region. The importance of the top surface layer and its reconstruction is demonstrated by theoretical simulations. Enhanced contributions of photoelectrons from individual subsurface layers in specific directions offer a way to investigate the desired subsurface atomic layers.
