Estimation of the pulse width of x-ray emission from Xe clusters excited by a subpicosecond intense Ti:sapphire laser pulse

The pulse width of $\mathrm{Xe}(M)$ emission, whose photon energy is $\ensuremath{\sim}1\mathrm{keV},$ from Xe clusters excited by a subpicosecond intense laser pulse was estimated to be shorter than 100 ps. While that of $\mathrm{Xe}(N)$ emission, whose photon energy is $\ensuremath{\sim}100\mathrm{eV},$ was longer than 1 ns. The theoretical estimation of radiative recombination rates suggests that the observed keV x ray is a prompt x ray.