Intrinsic photoconductivity of hexagonal ice

Abstract

It is found that the electric conductivity of ice changes appreciably upon its illumination in the vacuum ultraviolet spectral region. The changes observed have reversible and persistent parts (after switching off light). Spectral and kinetic characteristics of the photoconductivity (PC) of ice are presented. A PC maximum corresponds to a photon energy hv ≈ 6.8 eV. The dependence of the reversible part of PC on the water purification techniques is studied. It is assumed that the phenomenon observed is independent of the impurity contents and in this sense PC is intrinsic. Special investigations are devoted to possible photoelectric phenomena at the ice‐‐electrode interfaces. A monotoneous accumulation of small quantities of H2O2 in ice is observed when increasing the light exposition. This is an evidence for the participation of “free” radicals OH. in the PC processes. It is concluded that conduction electrons and Bjerrum defects (L‐ und D‐defects) cannot be nonequilibrium charge carriers.

Action of electric fields on the plastic deformation of pure and doped ice single crystals

“…A comparison of experimental results on dislocation velocities in ice with the simple theoretical predictions of Peierls' model revealed their significant quantitative inconsistency (Shearwood and Whitworth 1991). Also it is not clear how the mobility of dislocations in ice with high Peierls barriers can be changed by doping with HF (reported after Glen and Jones by Mai, Perez, Tatibouet and Vassoille (1978)) or by changes in conductivity c r , .…”

“…Motion of a dislocation together with its expended non-crystalline core must be difficult because of the necessity to move through a crystal boundary between two phases. These ideas are the basis of a third model called 'the non-crystalline core model' proposed by Perez, May and Vassoille (1978). While there are no very obvious connections between dislocation mobility and om impurity atoms or molecules absorbed by the dislocation core might change the core size and mobility of the dislocation.…”

“…However, such doping introduces other changes such as impurity atoms and interstitials into the structure, as well as concentrations of the mobile protonic point defects. Possibilities for verification of the models appeared after techniques had been developed to produce reversible changes in the concentration of the minority charge carriers by proton injection from palladium electrodes (Petrenko, Glen and Whitworth 1983), by the use of intrinsic (Khusnatdinov, Petrenko and Turanov 1990) or impurity (Ebinuma, Maeno and Petrenko 1986) photoconductivities of ice, or by recombinational injection of ions from electrodes into ice (Petrenko and Chesnakov 1990). It is even more important that a technique for the reversible change in majority charge carriers (and hence om change) has been recently invented that uses the application of d.c. electric fields across thin ice samples (Petrenko and Schulson 1992).…”

Approche physique du développement de streamers positifs sur une surface de glace =

“…D'autres études ont aussi montré que des radiations UV émises dans la gamme de 175 à 190 mn peuvent générer une photoconductivité dans la glace même si celle-ci diminue après une illumination prolongée [130]. Il a aussi été observé que majoritairement, ce sont des porteurs de charge négative qui sont créés et qu'ils diffuseraient jusque dans les régions non illuminées [28,131].…”

Electron energy spectrum of ice

“…Although the electronic structure of ice determines such important phenomena as ultraviolet optical absorption [5], photoluminescence [6], photoconductivity [7,8] [9,10], theoretical calculations of electron spectra of ordinary ice Ih have never been done. One reason for the practical absence of such papers is the disorder in the ice proton subsystem, which makes the application of any method using periodicity and Bloch's theorem impossible.…”