Tunnelingionisierung

Tunnelingionisierung is a process in atomic and molecular physics where an electron escapes from an atom or molecule not by acquiring enough energy to overcome the potential barrier, but by quantum mechanical tunneling through it. This phenomenon typically occurs when the atom or molecule is subjected to a strong external electric field, such as that produced by an intense laser pulse. The electric field distorts the potential well that holds the electron, making it effectively thinner and allowing for a non-zero probability of the electron tunneling out.

The probability of tunneling depends exponentially on the strength of the electric field and the binding energy of the electron. At lower field strengths, the process is less likely, while at very high field strengths, the potential barrier can become so thin that tunneling becomes a dominant ionization mechanism, often referred to as non-linear tunneling ionization. This is in contrast to multiphoton ionization, where an atom absorbs multiple photons to gain sufficient energy to overcome the ionization potential, and to optical-field ionization, which can describe both multiphoton and tunneling ionization depending on the laser intensity and pulse duration. Tunneling ionization is a crucial process in understanding the interaction of matter with intense laser fields and is important in fields like high-harmonic generation and attosecond science.