An Electron in Water

What happens when a fast-moving electron hits water?

This question is important for understanding the effects of ionizing radiation, but it’s also just cool. I learned the answer here:

• H. Haberland and K. H. Bowen, Solvated electron clusters, Springer Series in Chemical Physics 56 (1994), 134–153.

There are four stages. To get a feel for these, it helps to remember that a femtosecond is 10-15 seconds. This is roughly the time it takes for light to travel a third of a micron—about 5000 times...