Suppression of multiphoton ionization with circularly polarized light

Multiphoton ionization in xenon has been studied using 1064 nm circularly polarized coherent light, producing electrons with energies up to 15 eV. A strong suppression of the cross section is observed for electrons below 4 eV, but not for linearly polarized light at the same intensity. We show that if the electrons are emitted in single step nonresonant coherent processes, rather than stepwise excitation, the centrifugal potential barrier in the atomic Hamiltonian produces this suppression.