Branching into two spin-orbit levels in ionization of Kr and Xe in intense UV laser fields

Nakano, Motoyoshi; Otobe, Tomohito; Itakura, Ryuji

We have studied branching into two spin-orbit levels (J = 3/2 and 1/2) of Kr and Xe in induced by intense ultra-violet laser pulse (398 nm, 80 fs) with photoelectron momentum imaging. In the case of Xe, when the laser intensity increased from 9 to 26 TW/cm, the branching ratio [J=3/2]/[J=1/2] in the five-photon ionization increases from 0.65 to 1.25. In the case of Kr, the ratio is almost constant in this intensity range, but the angular distributions change significantly. We performed ab initio calculation and compared it with the experimental results.