Tuning Bound Atomic States to Multiphoton Absorption and Susequent Ionization

S. H. Lin, Yuichi Fujimura, Hans Jürgen Neusser +1 more

G. A. Delone, Nikolai B. Delone

Kiyonobu Nagaya, Denys Iablonskyi, Nikolay V. Golubev +18 more

In high-intensity laser light, matter can be ionized by direct multiphoton absorption even at photon energies below the ionization threshold. However on tuning the laser to the lowest resonant transition, the system becomes multiply excited, and more efficient, indirect ionization pathways become operative. These mechanisms are known as interatomic Coulombic decay (ICD), where one of the species de-excites to its ground state, transferring its energy to ionize another excited species. Here we show that on tuning to a higher resonant transition, a previously unknown type of interatomic Coulombic decay, intra-Rydberg ICD occurs. In it, de-excitation of an atom to a close-lying Rydberg state leads to electron emission from another neighbouring Rydberg atom. Moreover, systems multiply excited to higher Rydberg states will decay by a cascade of such processes, producing even more ions. The intra-Rydberg ICD and cascades are expected to be ubiquitous in weakly-bound systems exposed to high-intensity resonant radiation.

Anne L’Huillier, Louis A. Lompre, G. Mainfray +1 more

This paper describes the production of multiply charged ions induced by collisionless multiphoton ionization of rare gases at 532 and 1064 nm. The production of multiply charged ions emphasizes atomic properties and laser characteristics. Multiphoton absorption is expected to selectively excite high ionic energy states, which could induce a stimulated emission in the extreme ultraviolet.

I. Berson

Henrik Stapelfeldt, Dimitrios G. Papaioannou, Lambertus D. Noordam +1 more

We have studied multiphoton ionization of Ba 6snl Rydberg states by intense ps pulses and have shown that the duration of the laser pulse compared to the orbit time of the Rydberg electron determines the laser-atom interaction. For high-n states with a long orbit time, the loosely bound Rydberg electron is not affected by the intense laser pulse. Instead the inner electron is ejected by absorption of five photons, leaving the ${\mathrm{Ba}}^{+}$ ion in a Rydberg state. For low-n states the outer electron is ejected and the residual ${\mathrm{Ba}}^{+}$ ion can subsequently be multiphoton ionized to ${\mathrm{Ba}}^{++}$.