Aller au contenu principal

PSI2 Program DYMCOM

Specific Cases

A short list of specific examples follows.

1. Kelvin to sub-mK chemistry

The challenges between experiments and theory are numerous :

  • The CERISES and other similar experiments at FELIX.
  • Low-T jets, traps, (including mixed neutral-ion traps) and storage rings present many experimental challenges to be met
  • Identical particles low-T chemistry.  XHn+,  Hn+  vs. Rbn+  . Roles of electronic, nuclear spin, and atomic weight. Experiments and astro applications. Bose-Einstein condensation of alkaline mole­cules. Deuteration and spin scrambling through exchange reactions. Scaling of Zero-point en­ergy.
  • Typical ions or ion molecule reactions of interest and amenable to experiments are, in the Kel­vin regime:

       He-H3+ and    H2-FeO+ ;    Binding energy of NH+ (photo dissociation);
       Reaction of N+ + H2 and isotope variants.
       Radiative association C+ + H, H+ + H2, H3+ + He,    Reactions of ions with slow H-atoms
  • High precision long-range PES, including PES for open shell interacting molecules.
  • Reaction mediated by tunnelling. Several prominent examples in astrophysics (H + CO). Com­pound difficulty: N+H2 —> NH2 + hv (spin-orbit+tunneling). Relevance of very minor rates, like forbidden inter-system crossings.

2.  Detachment and recombination. Non Born-Oppenheimer effects are key, as well as proper inclusion of various Rydberg channels in incoming and/or outgoing channels.

  • Low-T recombination e- + M+ —> M + hv / A +B / A’ + B’ : Rates ,  branching ratios.  Experi­ments  (traps, ion storage ring) and observational cases, in plasma and astrophys­ics.
  • Dissociative detachment, with similar importance of branching ratios: M+ e-  —> M  + 2e/ A+B+2e-  . M- + X —> A + B  + X + e-.  Experiments in traps, some astrophysical observa­tions

3. Reactivity

Interesting (and challenging) are reactions involving radicals, all the more if activation en­ergy is absent, but with a submerged barrier.  These reactions dominate chemistry at low enough temperatures: (i) Compute reliably and economically such common land­scapes (ii) Investigate the importance of roaming type mechanisms at low-T near thresh­old, in particular the existence, nature and manifestations of quantum roam­ing.