Mainz 2026 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 30: Poster – Molecular Spectroscopy

MO 30.3: Poster

Donnerstag, 5. März 2026, 17:00–19:00, Philo 1. OG

Experimental setup for recurrent fluorescence studies of cold trapped molecular ions — •Nariste Asanova, Surabhi Gupta, Suvasis Swain, Henrik Haak, Gerard Meijer, and Jascha A. Lau — Fritz-Haber-Institute der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany

Emission lines in the visible and infrared range detected in interstellar environments are frequently attributed to carbon-rich species, such as polycyclic aromatic hydrocarbons (PAHs) and linear carbon chains. Therefore, it is important to study the radiative cooling process of these molecular systems. We are developing a new experimental setup that employs a linear Paul trap, in which a sufficiently dense, cold ion cloud is trapped at the interaction center to allow for dispersed fluorescence spectroscopy in millisecond timescale. The main focus is on recurrent fluorescence, which has been recently experimentally proven. The ion optics of the ion source, mass spectrometer, and the ion trap were optimized in SIMION 8.2 to ensure efficient loading of the trap. Once the ions are inside the trap, a short pulse of cold (4 K) He/H2 buffer gas is released, resulting in internal and translational cooling of the ions through collisions. The gas pressure must decay on a short timescale (~10 ms) to prevent quenching of the fluorescence signal. Time-dependent pressure curves for each stage were modeled using Molflow+ to optimize gas conductance out of the trap while minimizing stray light. The signal is measured by a monochromator, with time-resolved single-photon counting using a photomultiplier tube and dispersed spectra recorded by an iCCD camera.

Keywords: Astrochemistry; Radiative Cooling; Recurrent Fluorescence; Cryogenic Ion Trap; Buffer Gas Cooling