Interfering Bloch waves in a 1D electron system

Using low-temperature scanning tunnelling spectroscopy we have studied the spatial variation of confined electronic states between neighbouring atomic chains on a Ge(001)/Pt surface. The quasi-one-dimensional electronic states reside in the troughs between the atomic chains and exhibit a profound Bloch character along the chain direction. In the proximity of defects an enhancement of the oscillatory standing wave pattern in the density of states is found. The spatial variation of the standing wave pattern can be explained by an interference of incoming and reflected Bloch waves.