Theory of high intensity, multiphoton processes in Alkali metal atoms

V. V. Semenov

Natalia Vinci

The aim of this thesis is to extend the study of multiphoton processes to the heavier negative ions of the alkali-metal atoms and thus, Na"- and K"- were natural candidates for this investigation. The main idea is to achieve an homogeneous description of negative alkaline ions and their response to an intense laser field. This idea has been suggested by recent experimental findings for negative alkaline ions which have revealed a rich structure of their scattering and photodetachment spectra, showing the existence of high-lying temporary negative ion states. Moreover, dramatic effects due to excess photon detachment have been observed yielding additional information on the dynamics of these highly correlated systems

R. N. Compton, Michael A. Duncan

Mette B. Gaarde, Kenneth J. Schäfer

In the strong-field regime a single multiphoton resonance can enhance many harmonics of the fundamental laser frequency simultaneously. We demonstrate that an alkali-metal atom driven by an intense, ultrafast midinfrared pulse is an ideal system for observing this effect by calculating the response of potassium atoms to radiation that is nearly three or five photon resonant with the $4s\ensuremath{-}4p$ transition. We find that all the harmonics through at least the 17th are enhanced over a wide range of intensities, and that the resonance width of the enhanced harmonics is governed by the lifetime of the multiphoton resonance.

L. N. Labzovskiǐ, N. S. Iakovleva

Nikolai B. Delone, В. П. Крайнов