Supressing dielectric constant of water?

[excalibur313]

Hey Everyone. I am doing a project proposal where I am calculating the coupling efficiency between a quantum dot and a wire and I need to enter in values for the dielectric constant of the wire and the surrounding medium. I am working off a paper (doi:10.1103/PhysRevB.76.035420) where he uses the dielectric constant for the surrounding medium to be 2. I would like to do this in water which has a much higher dielectric constant and unfortunately it seems to kill off the really efficient coupling that I was getting. Does anyone know of a way to suppress the dielectric constant and to somehow quantify how low I can get it? I know salt will depress it, but how much would I expect? I read that if I get water at a supercritical phase I can get it pretty low, but does anyone know of any other way? Thanks a lot for your help!

 

[mda]

The dielectric "constant" of water is very much a function of frequency... presumably if you are interested in quantum dots you'll be using optical frequencies?
In that case the permittivity of water is actually rather low (about 1.8).