Molecular ions and nanoparticles in RF and AC traps

This report summarizes recent advances in using innovative storage devices based on inhomogeneous, time-dependent electric fields. Electrode arrangements include quadrupoles, linear octopoles, higher-order multipoles, or a series of ring electrodes. Applying suitable oscillating voltages to such structures, with frequencies ranging from GHz via MHz to a few Hz, a variety of charged particles can be confined ranging from electrons via molecular ions to nanoparticles with masses of more than 10(10) u. This contribution give a short summary of the theory, especially the effective potential approximation. The features of the technique are illustrated by several examples such as trapped ion beams, buffer gas cooling of ions in a 22-pole trap, and nanoparticle mass spectrometry in a quadrupole. Recent experimental results include growth of structures, isotope enrichment, and submonolayer gas ad- and desorption on a stored 500 nm SiO2 particle. In the summary a few hints concerning ongoing experiments are given such as laser induced reactions, combination of traps with atomic beams, state-selected perturbation of a trapped low temperature ensemble with an infrared laser, and future trends in nanoparticle research.