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Re: WSN: high field dielectric behaviour of water (fwd)

Sender: bruce_bush@merck.com (Bruce Bush)
Subject: Re: WSN: high field dielectric behaviour of water

 huinink@metten.FenK.WAU.NL writes: 

> It is believed that the dielectric constant of water decreases monotone
> with the field strength, thus normal saturation. This seems general 
> accepted, but why?  ..
> question II:   Has anybody more references about this subject?
> question III:  Is extrapolation of these results to higher field strength
> (10 8 V/m) allowed?
> I ask this questions because I've calculated with a statistical
> thermodynamical lattice model for water. With this model I've predict 
> strange saturation behaviour, a maximum in the saturation curve. The low 
> field dielectric behaviour (even as a function of the temperature) has 
> been predicted rather well. I think that maximum arises as a consequence 
> of the strong hydrogen bonding ...

There have been simulation studies of dielectric response to ions or
polar molecules as one mutates the charges.  I believe that they indicate
a large contribution from the translational motion (electrostriction)
which compensates, up to a point, for the saturation of the orientational
(mostly dipolar) response, so the total response is almost linear up to
a charge of ~1.0 on an atomic ion.  There may have been many such studies;
see JPC ~1990, authors Jayaram; Beveridge, D. ; and others by 
Honig, B.; Sharp, K;, Nicholls, A.
Response to a point charge in a spherical solute may depend on radius and
thus may differ from response to a spatially uniform field (infinite radius).

A maximum (turnover) in the response function would seem to indicate 
peaks in the density of states induced by the applied field.  That could
involve different networks of hydrogen bonds.

A simulation of water (ice) published in Science late 1994 claimed to be
the first to show a first-order transition.  In fact the simulation
involved very large applied field, to an oriented state (not ice I),
indicating very different h-bond topologies of normal water vs. water
responsind to a strong uniform field.  A strong, radial field may be
something yet again .

These are just general points.  Water experts will have more specific
useful facts to cite, I'm sure.

Regards,

/ Bruce /
bruce_bush@merck.com  (908) 594-6758 Merck Research Labs Rahway NJ 07065