The photodissociation of N2O is studied by wave packet calculations using a global three-dimensional potential energy surface for the first excited A1′ state. It is shown that the weak vibrational structures of the absorption cross section are caused by large-amplitude NN stretch motion, combined with strong excitation of the bend as well as the O–NN stretch. Weakening of the NN bond toward the N+NO channel is the necessary prerequisite.

We have calculated state-selective excitation cross sections in fully stripped Li3 +, Ne10 + and Ar18 ++H(1s) collisions from low (1 keV/amu) to high (1000 keV/amu) impact energies, relevant in fusion plasma diagnostics. In order to cover this broad impact energy range, three different theoretical methods have been employed: the semi-classical molecular and one-centre atomic-orbital close-coupling approaches, and the classical trajectory Monte Carlo method. Recommended partial excitation cross sections are provided by merging the results obtained with each method in the energy range where they are the most accurate.

El acceso a la versión del editor puede requerir la suscripción del recurso E-mail: ismanuel.rabadan@uam.esAbstract A quantum-mechanical study of the predissociation of H 2 O + (B 2 B 2 ) is carried out by using wave packet propagations on ab initio potential energy surfaces connected by nonadiabatic couplings. The simulations show that within the first 30 fs, 80% of the initial wave packet is transferred from theB 2 B 2 to theà 2 A 1 electronic state through a conical intersection. A much slower transfer (in the ps timescale) from theà 2 A 1 to thẽ X 2 B 1 state due to a Renner-Teller coupling determines the fragmentation branching ratios, which are in accordance with the experimental measurements.

We perform monocentric close-coupling calculations to obtain partial and total cross sections for excitation and electron loss in bare A q+ +H͑1s͒ collisions, with 1 ഛ q ഛ 6, for intermediate ͑E =40 keV/amu͒ to high ͑E = 7000 keV/ amu͒ impact energies. We use underlying basis sets of even-tempered Slater-type orbitals and confined spherical Bessel functions and compare the accuracy of the cross sections derived from these two implementations. Scaling rules are then established for the partial excitation cross sections of interest in fusion plasma research. We also undertake impact parameter first-Born calculations using the spherical Bessel underlying set to compare in the course of collision the close-coupling and perturbative descriptions of the ionization process.