Multiphoton induced x-ray emission from Kr clusters on<i>M</i>-shell (∼100 Å) and<i>L</i>-shell (∼6 Å) transitions

Experiments demonstrating the role of cluster formation on multiphoton-induced x-ray emission and the scaling of this phenomenon into the kilovolt range have been performed on Kr. For the Kr M shell, augmentation of ${\mathrm{Kr}}_{\mathit{n}}$ formation leads to a large increase in ${\mathrm{Kr}}^{9+}$ (4p\ensuremath{\rightarrow}3d) emission (\ensuremath{\sim}100 \AA{}) and the appearance of a strong band at \ensuremath{\sim}90 \AA{}. The observation of L-shell transitions (\ensuremath{\sim}5--7.5 \AA{}) demonstrates the scaling of this phenomenon into the kilovolt region and leads to the conclusion that the interaction produces direct inner-shell excitation with the emission of prompt x rays.