The total and partial photodissociation cross sections of the molecular ion HeH + are computed by timedependent methods for fragmentation into the excited shells n =1,2,3 up to a photon energy of 40 eV. 1 ⌺ + and 1 ⌸ states are considered for parallel and perpendicular transitions for different initial rotational or vibrational excitations. Nonadiabatic radial and rotational couplings are taken into account. The results from coupledchannel equations are compared with the Born-Oppenheimer approximation. A time-dependent calculation with a femtosecond laser pulse is carried out to simulate a recent crossed beam photodissociation imaging experiment with vacuum ultraviolet free-electron laser ͓H. B. Pedersen et al., Phys. Rev. Lett. 98, 223202 ͑2007͔͒. The dominance of photodissociation perpendicular to the photon polarization is confirmed.
The charge transfer in low energy (0.25 to 150 eV/amu) H(nl) + He + (1s) collisions is investigated using a quasi-molecular approach for the n = 2, 3 as well as the first two n = 4 singlet states. The diabatic potential energy curves of the HeH + molecular ion are obtained from the adiabatic potential energy curves and the non-adiabatic radial coupling matrix elements using a two-by-two diabatization method, and a time-dependent wave-packet approach is used to calculate the stateto-state cross sections. We find a strong dependence of the charge transfer cross section in the principal and orbital quantum numbers n and l of the initial or final state. We estimate the effect of the non-adiabatic rotational couplings, which is found to be important even at energies below 1 eV/amu. However, the effect is small on the total cross sections at energies below 10 eV/amu. We observe that to calculate charge transfer cross sections in a n manifold, it is only necessary to include states with n ′ ≤ n, and we discuss the limitations of our approach as the number of states increases.
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