Experiments with Trapped Ions and Nanoparticles

Summary

This contribution summarizes experimental work which has been performed predominantly in our laboratory using ion guides and specific traps for studying ions, molecules and dust particles under astrophysical conditions. After a short reminder of the basics of the technique and a brief discussion of our newest device, the nanoparticle trap, we shall review experimental results for low temperature gas phase collisions with H₂. In the last part we will summarize our present activities related to chemistry involving cold H atoms.

Introduction

Despite the fact that our knowledge on the role of hydrogen in space has significantly increased in recent years due to a combination of extensive new observations and astrophysical model calculations with fundamental theory and detailed innovative experiments, there are still many unsolved problems related to the interaction of H or H₂ with ions, radicals, surfaces and also photons. The most obvious example is the formation of H₂ itself; other examples include specific state-to-state cross sections, ortho-para transitions in H₂, H-D isotopic scrambling, formation and destruction of the molecule, or the role of hydrogen clusters and anions. In addition to gas phase reactions we will discuss in this paper our most ambitious goal, the detection of catalytic formation of H₂ molecules on an interstellar dust analogue localized in a cold trap.

Experimental: Ion guides and particle traps

Inhomogeneous RF or AC fields

From the point of view of experimental techniques, our research is predominantly based on the use of specific inhomogeneous, time-dependent, electrical fields, E₀(r,t) = E₀(r) · cos(Ωt).