Linear- and circular-polarization photoionization angular distributions in H2 and H2+ by attosecond xuv laser pulses

Numerical solutions of the time-dependent Schroedinger equation, using a new unitary numerical method, are used to obtain gauge-independent photoionization angular distributions for two-dimensional (planar) models of aligned H2 and H2+ molecules in different electronic states. Simulations are performed with few-cycle attosecond (as) extreme-ultraviolet (xuv) laser pulses at wavelengths λ= 10 nm [ω= 4.56 a.u. (atomic units), τ=2π/ω= 1.38 a.u. = 33.4 as], and λ= 5 nm (ω= 9.11 a.u., τ= 16.7 as) for linear and circular polarization ionizations at Re=1.675 a.u., where molecular orbital configurations dominate for which the electron wavelengths λe≥Re and at large internuclear distance R=10 a.u. (λe<R) where Heitler-London atomic configurations including ionic states H+H- are more appropriate. The simulations allow one to investigate the effects of electron correlation and entanglement in H2 at different R due to electron spin exchange as compared to the delocalized one-electron H2+ system. An ultrashort (delta function) pulse model is used to interpret interferences in momentum distributions.