The Delhi Penning-trap facility for interaction studies of astro-chemically relevant molecules with relativistic electrons

ABSTRACT We present the Delhi Penning-trap set-up as a versatile instrument for well-controlled studies with atomic and molecular ions that interact with relativistic electrons. These are an abundant part of the high-energy radiation in space and of cosmic rays in planetary atmospheres. The set-up allows for laboratory astro-chemistry and astro-physics to be performed at an electron-beam facility, such as the Delhi Light Source free-electron laser at the Inter-University Accelerator Centre in Delhi, India, that provides electrons in the MeV range of kinetic energy. Since information in this region of interaction energies is sparse, it opens up new possibilities for laboratory studies of interactions that are ubiquitous in space and highly relevant for an understanding and modelling of a broad range of phenomena. We show the status of the set-up and offline measurements performed as a proof of principle. We discuss one specific application in detail, namely the topic of recurrent fluorescence, for which trap measurements promise first direct long-term observations. A flexible model and Monte Carlo simulations of recurrent fluorescence from polycyclic aromatic hydrocarbons are presented and benchmarked against previous measurements.