# Thinking about electronic collisions with hydrogen.

1. May 5, 2010

### IHateMayonnaise

This seems like such a simple question and I feel like an idiot asking it, but here goes:

If we have a hydrogen atom (not molecule) at "rest" and we shoot an electron at it with a certain known energy, what could happen?

To me, it seems as though there are two distinct outcomes; either the electron is absorbed in an inelastic collision, or scattered in an elastic collision.

What are the approximate threshold values for these cases? I.e. if I send in an electron that has energy less than the ground state of hydrogen (say 5 eV) it seems to me that scattering would occur. And it seems like this would be the case all the way up to right before 13.6ev, and anything more would result in absorption.

Is my thinking flawed? Should I be thinking more of what the ionization potential of what $H^-$ should be?

Thanks Yall

IHateMayonnaise

2. May 6, 2010

nobody? :(