Radiative autoionization - A proposal for the construction of short-wavelength lasers

Radiative autoionization (RA) is a spontaneous decay mechanism of highly excited states, whereby the atom or molecule makes a radiative bound- (or quasi-bound-) free transition, emitting a photon and an electron at the same time. Calculations show that, for each transition, the intensity of the emitted radiation peaks on the short-wavelength side. Since RA involves a final empty state, population inversion is achieved once the initial state is populated. The basic lasing condition can thus be satisfied automatically. The phenomenon is analogous to the radiative dissociation process which is the physical mechanism for the excimer laser. Examples are given for the H(-) and He 2p2 3P, He(-) and Li 2p3 4S0, Li and Be(+) 1s 2p2 2P, He 2p 3p 1P, and 2p 3d 1D0, as well as for the Li 1s 2s 2p 4p0 state which undergoes relativistic RA.