Excitation of the triplet 2p4(3P)3s2 autoionizing state of Neon by molecular orbital electron promotion at solid surfaces

We address the long standing issue of the dominant excitation of the triplet 2p4(3P)3s2 state in the scattering of Neon projectiles from Magnesium, Aluminum and Silicon surfaces, which is not predicted by the Fano-Lichten Molecular orbital promotion model. We measured autoionization spectra from the triplet and the singlet states of Neon excited at Al and Mg surfaces. The measurements show that the triplet excited state is produced locally at the collision site, supporting the physical picture of an Auger rearrangement converting the singlet state into the triplet while the colliding atoms are still coupled in the quasi-molecular system.