# How to relate laser pulse characteristics to the degrees of ionization of a target (i.e. how many electrons get removed per atom)?

Say I have a lithium foil as a target for a laser. Li has $$3$$ protons and $$3$$ electrons and therefore $$3$$ degrees of ionization associated with $$3$$ ionization energies (for removing the first, second and third electron).

How do I relate the characteristics of the laser to the ionization outcome in the target? In other words, how do laser parameters such as pulse length and shape, photon energy, and intensity affect how many of the Li atoms in my target get ionized to the $$1st$$ , $$2nd$$ , and $$3rd$$ degree?

I realize that a comprehensive answer may be complicated but perhaps you can share how you recommend to think about the problem and/or link to useful references.

• A comprehensive answer is much too complicated for a single thread here. But, as a start: if you have lithium foil, the lithium atoms are not in isolation, and the electrons (particularly the $2s$ electrons, which form the conduction band) are not assigned to individual atoms. The "three ionization energies" you mention apply for isolated atoms in gas phase. So there's a lot to re-think there. Nov 25 at 18:23
• I second @EmilioPisanty...I am surrounded by people that do this kind of things all the time and the typical way to know which kind of degree of ionization will come out of the targets is typically by actually performing the experiment and back it up by very long computational simulations after one knows everything surrounding the experiment. Because when you go to high field strengths lots of complicated things happen. Nonetheless, a good starting point is always literature. Nov 26 at 21:40

Three different energies are needed to remove the $$1^{st}$$, $$2^{nd}$$, and $$3^{rd}$$ electrons. This means photons with three different wavelengths are needed.