STM-induced desorption of hydrogen from Co nanoislands

Using low-temperature scanning tunneling microscopy (STM) and spectroscopy, we have studied the effects of H2 adsorption at 10 K on the electronic properties of nanometer-scale triangular Co islands deposited on Cu(111). Before H2 adsorption, two reported surface states are observed. However, after adsorption, both are quenched. In addition, we found that total removal of the adsorbate from the surface of the islands can be induced by the STM tip. As the tip affects only selected islands without perturbing neighboring islands, this process can be used to individually control the electronic properties of the Co nanoparticles. In particular, total desorption fully recovers the surface electronic features of the clean islands. Direct and indirect desorption mechanisms are discussed in relation to these experimental data.