Abstract
When atoms and molecules are exposed to intense low frequency laser fields, the dominant response is sequential tunnel ionization of charge states with increasing ionization potential. Sequential ionization is assumed to proceed as separate one electron processes. The theoretical analysis developed here reveals that in complex systems sequential tunnel ionization can be inhibited by Coulomb blocking. When ionization potentials of subsequent charge states are close to each other, multiple tunneling events can occur during a half cycle and in close proximity, so that a tunneled electron can block the next tunneling electron. In sub-nm clusters driven by near infrared single-cycle pulses, Coulomb blocking reduces two-electron sequential tunneling by up to 2-3 orders of magnitude.
Highlights
We start by introducing the quasi-classical, quasi-static approach used to model Coulomb blocking (CB) of tunnel ionization
In the case of near-IR wavelengths, we find that CB appears most pronounced in smaller clusters, driven by single-cycle laser pulses with moderate field strengths, in which case electrons have little opportunity to avoid each other
We start by introducing the quasi-classical, quasi-static approach used to model CB of tunnel ionization
Summary
We start by introducing the quasi-classical, quasi-static approach used to model CB of tunnel ionization. This increases the likelihood of ionizing more than one electron during a half cycle. The quasi-classical, adiabatic approach developed here is limited to two electrons tunneling from a model cluster.
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