I'm trying to interpret a research paper on single photon ionization using extreme UV attosecond laser pulses, and I realized I have some very basic questions concerning electrons in an atom. Technically, the answers to these questions are found online and in the literature, but the wording always tends to be the same - and it's just not doing it for me. A short answer to any of these in your own words would be greatly appreciated! 1.) Do bound electrons in an atom follow a closed Keplerian orbit around the nucleus? 2.) Can/should an electron (bound or unbound) always be described as an "electron wave packet"? Is a bound electron in an atom always a "Gaussian wave packet" with minimum uncertainty that is nondispersive? 3.) Say I shine laser light on a Hydrogen atom. a.) If the frequency of the light is too low, the electron will need to absorb many photons to gain enough energy to tunnel through the Coulomb barrier and ionize the atom. How is this explained in the wave-packet formalism? Is there a relationship between coherent states and whether or not the electron overcomes the Coulomb barrier? b.) If the frequency is high enough (extreme UV range), then the electron may absorb enough energy to immediately escape the Coulomb potential barrier. How will the electron wave-packet after ionization be different in this case than in the case of part (a)? Any answers (even partial) to these questions would be extremely helpful!