Amorphous Water-Ice Relaxations Measured with Soft-Landed Ions

Abstract

${\mathrm{D}}_{3}{\mathrm{O}}^{+}$ and ${\mathrm{Cs}}^{+}$ ions $(\ensuremath{\le}1\mathrm{eV})$ were soft landed on vacuum-deposited amorphous water ice at 30 K. The samples charged capacitively with an initial dielectric constant of 2. Then the voltage was measured via a Kelvin probe while the sample temperature was ramped. A sharp drop in voltage occurred near 50 K, due to dielectric responses occurring at much less than the expected 135 K. This was due to relaxations of the highly strained amorphous ice. Preannealing the ice could move the electrical relaxation up to as high as 120 K. Ion migration through the ice was not observed below 190 K.