above threshold ionization

It is concerned with processes such as ionization, Above threshold ionization and excitation by photons or collisions with atomic particles.

The other is doing experiments with few cycle pulses, like above threshold ionization, attosecond pulses, highly efficient nonlinear optics or high harmonics generation.

Above threshold ionization (ATI) is an extension of multi-photon ionization where even more photons are absorbed than actually would be necessary to ionize the atom.

Within atomic, molecular, and optical physics above threshold ionization (ATI), which was first observed in 1979, is a multi-photon effect where an atom is ionized with more than the required number of photons.