  Femtosecond high-order harmonic transient absorption spectroscopy is used to
resolve the complete |j,m> quantum state distribution of Xe+ produced by
optical strong-field ionization of Xe atoms at 800nm. Probing at the Xe N_4/5
edge yields a population distribution rho_j,|m| of rho_3/2,1/2 : rho_1/2,1/2 :
rho_3/2,3/2 = 75 +- 6 : 12 +- 3 : 13 +- 6 %. The result is compared to a tunnel
ionization calculation with the inclusion of spin-orbit coupling, revealing
nonadiabatic ionization behavior. The sub-50-fs time resolution paves the way
for table-top extreme ultraviolet absorption probing of ultrafast dynamics.
