Electron damage to supported ice investigated by scanning tunneling microscopy and spectroscopy

We study the interaction of low-energy electrons with crystalline ice (${\mathrm{D}}_{2}\mathrm{O}$) on Cu(111) by low-temperature scanning tunneling microscopy and spectroscopy. Electrons induce dissociation of the molecules with a threshold of $\ensuremath{\approx}3\text{ }\text{ }\mathrm{eV}$. The large dissociation yield of the order of ${10}^{\ensuremath{-}8}/\mathrm{\text{electron}}$ and the extended area of dissociation are attributed to a shift in conduction band during the dissociation. Voltage dependent differences in imaging of ice and dissociated ice are reflected in the spectroscopic signature.