Seminarium Optyczne
sala 1.03, ul. Pasteura 5
Gerard Meijer (Director at the Fritz Haber Institute of the Max Planck Society in Berlin)
Wall collisions with a laser-coolable molecule & ion formation via associative ionization
Molecular species that are suitable for direct laser cooling are typically considered lost or destroyed if they collide with an ambient temperature vacuum wall. I will report on wall collisions with aluminum monofluoride (AlF), a laser-coolable molecule that survives this process with unusually high probability. We characterize the trapping-desorption process for AlF with various wall materials and accurately determine its survival probability. We demonstrate accumulation of AlF molecules into an ambient temperature storage vessel at densities near 10^8 cm-3. This provides a route to compact, portable traps for neutral molecules.Some molecules have the unusual property that their dissociation energy is larger than their ionization energy. Their cations are stable against dissociative recombination with electrons, and can be efficiently formed via (laser-induced) auto-ionization or thermionic electron emission of their neutral counterparts. These cations can also be efficiently formed in - often overlooked - two-body associative ionization reactions. I will speculate in how far ion formation via associative ionization can explain the mere presence and relative abundance of several peculiar species in the outflows of stars.


