The cosmic dust experiment: a nanoparticle non-destructive mass spectrometer for astrochemical studies

Size-dependence of physicochemical processes on cosmic dust surfaces is a fundamental aspect for understanding the formation of complex organic molecules in space and improving the accuracy of astrochemical models. Most experimental studies of physical and chemical processes on cosmic dust grain surfaces are performed on thick multilayer ice mixtures (molecular solids) deposited on a substrate, which cannot fully capture the intrinsic characteristics of cosmic dust grains. We present here the design and implementation of a non-destructive mass spectrometer for charged nanoparticles, equipped with a triboelectric injection system, and capable of probing the influence of grain size and morphology on gas–surface interactions. The system consists of a split ring electrode ion trap housed inside a vacuum chamber. The nanoparticle mass and charge are determined from the change in secular frequency of its centre of mass following a charge stepping procedure. Its motion is monitored through the time-dependent scattered light of an incident 532 nm wavelength laser. The working principles of the experiment will enable measurements of binding energies of molecules on terrestrial dust analogues and the study of ice formation and surface reactions.