> I have personally noticed that the blue color only appears when the pH of the hyperquenched solution is higher than 7 or so. I assume this is because solvated electrons react with protons to form their conjugate base: the hydrogen atom. The latter species is highly reactive as well, but it is not colored.
We see a very strong dark blue in cryoSAXS experiments on lysozyme buffer at pH 4.5 (acetate) containing high glycerol content. We've also seen that color fade to light yellow/brown over time while in the cryostream once irradiation has stopped (I don't recall if that particular solution had protein or not). The blue color appears long before the Henderson limit and does not seem to affect the scattering profile.
I believe a similar effect is at work in bottle glass that has been exposed to sunlight for a long time - color centers. Blue ice seen in the far north however, appears to be purely a light-scattering phenomenon and not a result of trapped electrons.
> -James Holton
> MAD Scientist
> Todd Geders wrote: