The initial stages of the hydrogen-induced reconstruction of Pd(1 1 0) studied with STM

The hydrogen-induced reconstruction of the Pd(1 1 0) surface was investigated in situ with scanning tunneling microscopy (STM). Focusing on the initial stages of the restructuring, which ultimately leads to a stable (1 × 2) reconstructed surface, we find an exponential increase of the reconstructed surface area with hydrogen exposure, up to 8 Langmuir, which can be explained by an autocatalytic behavior. Moreover, the steps, especially those running along the [0 0 1] direction, play a distinctive role in the buildup of the (1 × 2) reconstruction.