Two-pathway interferences in photoelectron angular distributions induced by circularly polarized femto\-second pulses.

Following up on earlier work using linearly polarized radiation [1], we analyze the characteristics of atomic ionization produced by circularly polarized two-color femtosecond pulses. Two-pathway interferences between nonresonant one-photon and resonant two-photon ionization in the vicinity of an intermediate resonance are considered in detail for atomic hydrogen. Using circularly polarized radiation significantly increases the complexity of the problem, while opening up a rich field of possible further investigations [2]. The principal properties of the photoelectron angular distribution (PAD) are obtained by solving the time-dependent Schr\"{o}dinger equation and employing a second-order nonstationary perturbative approach. The dependence of the PAD on the intensities, helicities of the harmonics, pulse lengths, and carrier envelope phases is considered in detail. \par\noindent [1] A.N.~Grum-Grzhimailo, E.V.~Gryzlova, E.I.~Staroselskaya, J.~Venzke, and K.~Bartschat, Phys. Rev. A 91, 063418 (2015); erratum: Phys. Rev. A 93 (2016) 0199901(E). [2] N.~Douguet, A.N.~Grum-Grzhimailo, E.V.~Gryzlova, E.I.~Staroselskaya, J.~Venzke, and K.~Bartschat, Phys. Rev. A 93 (2016), in press.