▎ 摘　　要

We present the first study of quantum interference patterns at a bilayer-trilayer armchair interface, for different stacking sequences. Visualization using scanning tunneling microscopy and theoretical calculations provides direct evidence that near armchair edges electron behavior is dominated by the "hard" edge, where the layer is abruptly truncated, as opposed to the "soft" edges, where layers continue across the boundary. Intervalley reflection causes universal quenching of the wavefunction with a periodicity of three C atoms, while the exact interference patterns depend on the stacking sequence and appear to be robust to disorder and chemical terminations. (C) 2013 AIP Publishing LLC [http://dx.doi.org/10.1063/1.4802796]