Transport properties in water ice of hydronium and H-bonding defects are notoriously hard to study, and remain controversial. We present a new class of data using soft-landed hydronium ions (D3O+) deposited on crystalline expitaxially-grown, 600 to 5060 monolayer water (D2O) films. A work function probe is used to measure the ion motion and H-bond defect migration. In contrast to many previous notions we found: 1) The hydronium did not diffuse in crystalline water films up to at least 190 K. 2) D-defects diffuse at about 124 K at zero field. This temperature shifts linearly with field strength, extrapolated to zero K at 1.6 x 108 V/m. 3) Ice grown at 160 K and subsequently dosed with hydronium at 160 K shows an active dielectric constant (-1/T2) down to 30 K. This suggests that L defects have zero activation barrier (or tunnel) for their migration.
Revised: May 17, 1999 |
Published: April 1, 1999
Citation
Cowin J.P., A.A. Tsekouras, M.J. Iedema, K. Wu, and G.B. Ellison. 1999.Immobility of Protons in Ice from 30 to 190 K.Nature 398, no. 04/01/1999:405-407.PNNL-SA-30261.