Two-photon emission (2PE) is a process in which an electron transition between quantum levels occurs through the simultaneous emission of two photons. Two-photon emission is interesting because it ...

This means that each electron transition will produce a photon of a different frequency and hence a different colour. This causes line emission spectra to be produced, as shown below. This is not ...

This can result in the emission of an electron (called a photoelectron), but only if the photon energy is greater ... model using attosecond streaking or RABBITT (reconstruction of attosecond beating ...

This creates vacancies, leading to a cascade of electron transitions within the atom as electrons from higher energy levels drop down to fill the vacancy. The energy released during these transitions ...