Search for multiphoton-induced inner-shell excitations

Abstract

Photon-counting experiments have been conducted to test the conjecture that at sufficiently high laser irradiance, atomic inner-shell excitations can be induced by laser-driven outer-shell oscillations. Using KrF light at an irradiance \ensuremath{\approxeq}3\ifmmode\times\else\texttimes\fi{}${10}^{17}$ W/${\mathrm{cm}}^{2}$ on low-density noble-gas targets, we detect no prompt photons which are characteristic of inner-shell processes.