On The Model Of A Triatomic Hydrogen Molecule PDF Download

The triatomic hydrogen molecular ion H3+ is the simplest polyatomic molecule, besides its fundamental importance for quantum chemistry, it is one of the cornerstones of molecular processes in interstellar clouds. The dissociative electron recombination (DR) of H3+ is much studied, but still subject to a long-standing controversy. Modern ion storage rings equipped with electron coolers provide a relatively clean environment for DR measurements, given that the vibrational and rotational motion of the molecular ions can be controlled. Measurements using two different experimental approaches are presented, which were used to monitor H3+ internal excitations at the ion storage ring TSR of the Max-Planck-Institut fuer Kernphysik; the Coulomb explosion imaging technique confirmed vibrational cooling due to spontaneous decay within 2s of storage, while DR fragment imaging measurements indicated the existence of highly excited rotational states with energies up to 1eV (12000 K) after more than 10s. A comprehensive rovibrational excitation model, based on theoretical calculations of transition probabilities can explain the experimental observations. For future experiments, a cryogenic 22-pole ion trap was constructed, which is capable of preparing rovibrationally cold H3+ ions.