Ultrafast K-Shell Hole Creation from Laser Rescattering: Optimized Wavelength and Intensity Yields for Lithium to Uranium*

We present the yields of k-shell hole creation due to laser rescattering in strong and ultrastrong fields. Laser driven rescattering at higher energies, where k-shell ionization can occur, involves relativistic effects and the Lorentz force from the laser magnetic field. The predicted demarcation of higher energy rescattering interactions has been described by a Lorentz deflection parameter \footnote{M. Klaiber, et al, \textbf{Phy. Rev. Lett} 118, 093001} in atomic units $\Gamma_R=U_p^{3/2} V_{IP}^{1/2}/(3 c^2 \omega) = 1$ for ionization of an electron from a binding energy $V_{IP}$ by an external field, frequency $\omega$ and ponderomotive energy $U_p$. Surprisingly, laser driven rescattering near $\Gamma_R \sim 1$ is able to create k-shell holes in all atoms from lithium to uranium and extends rescattering physics from the deep IR ($\lambda = 10 \mu m$) to 4th generation x-ray FEL sources ($\lambda= 1 nm$). Our results compare favorably with measurements in krypton and neon \footnote{Y. Deng, et al, \textbf{Phy. Rev. Lett} 116, 073901}. We report the laser intensity and wavelength needed to create the greatest number of k-shell holes, which can be as great as $10^{-4}$ (k-shell holes / optic cycle) and provide examples across the periodic table including Li, Ne, Kr and U.