Classical trajectory picture of the autoionization event in He(23S)–D2 Penning ionization: collision energy dependence Original Research Article

A theoretical picture of the dynamics of the autoionization event He(23S)–D2(v″=0) → [He…D2+(v′)]+e− is obtained for the values of collision energy ranging from 20 to 150 meV. The treatment of the dynamics consists in 2D classical trajectory calculations based on static characteristics which include quantum mechanical treatment of the perturbed D2(v″=0) and D2+(v′) vibrational motion. The vibrational populations are dynamical averages over the local widths of the He(23S)–D2(v″=0) state with respect to autoionization to D2+(…He) in its v′th vibrational level, the Penning electron energies are related to the local differences between the energies of the corresponding perturbed D2(v″=0)(…He*) and D2+(v′)(…He) vibrational states. In accordance with recent experimental data on the He(23S)–H2(v″=0) isotopic variant of the system, the average Penning electron energies are found to increase smoothly with increasing collision energy and the vibrational populations for the nascent Penning ions D2+(v′)(…He) are predicted to be nearly independent of the collision energy.