A pulsed supersonic entrainment reactor for the rational preparation of cold ionic complexes

We describe an ion source for the efficient preparation of cold ion-molecule complexes, X-.M. The method relies on condensation of solvent molecules, M, onto argon-solvated ions, X-.Ar-m, where the X-.Ar-m species are formed in a primary expansion and the molecular partner, M, is interfaced to this flow in the hydrodynamic region by supersonic entrainment. This hybrid supersonic afterglow reactor provides a clean synthetic approach for both bare and argon-solvated complexes, where the latter are particularly useful since their structures can be characterized by nanomatrix infrared predissociation spectroscopy. (C) 2000 American Institute of Physics. [S0034- 6748(00)00801-2].