Information stored in quantum states of water fragments (Vol. 48, No. 5-6)

Typical example of a Boltzmann plot. The magenta curved line is a two temperature fit, where the blue and red straight lines are its components.

Does water have memory? Well, not in the usual sense. But it is known, that if you tear water molecules apart, the remaining fragments can tell you a story about how it happened. To investigate this phenomenon, a plasma reactor producing miniature lightnings in direct contact with water level was constructed. The electrical discharges are powerful enough to cause dissociation of water molecules in various ways. To facilitate the electrical breakdown, the atmosphere in the reactor was replaced by argon.

The water molecule can be broken by impact of sufficiently fast electron, absorption of deep UV photon or previously excited argon atom. Each of these processes has a different energy balance and the remaining energy is partially conserved in quantum states of the water fragments. By careful analysis of the light emitted by the relaxing OH radicals, we can disentangle the respective contributions to the total spectrum and calculate the portion of water molecules undergoing various dissociation mechanisms.

The water fragments really remember what preceded their creation and they let us know by emitting photons. The time scale for "forgetting" depends on the collisional rate, i.e. the pressure. At atmospheric pressure, the information can be kept for several nanoseconds.

J. Voráč, P. Synek, V. Procházka and T. Hoder, State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface, J. Phys. D: Appl. Phys. 50, 294002 (2017)