# WE STUDY COLD MOLECULES

Welcome to the Ion Spectroscopy and Laboratory Astrochemistry group

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# RESEARCH

Our research bridges the fields of molecular spectroscopy, nanoscience, chemical physics and astronomy. We develop and use state-of-the-art methods to synthesize and spectroscopically characterize gas-phase polyatomics under conditions relevant to those found in the interstellar medium. Our experiments make use of the unique properties of ion traps to store, cool and probe molecules at temperatures of just a few degrees Kelvin.

Motivation for our current activities comes from the recent discovery of C$_{60}$ in circumstellar environments and the identification of C$_{60}^{+}$ as the first carrier of several of the enigmatic diffuse interstellar bands (DIBs). We synthesize fullerenes, analogues and related molecular species and characterize them at low temperatures to enable direct comparison with astronomical observations. Ultimately, one of the aims is to gain insight into their role in the transportation of organic matter from circumstellar shells to regions where star and planet formation occurs.

Our scientific programme is also motivated by spectroscopic investigation of complex molecular ions, and many of the studied species are of fundamental interest.

# APPROACH

Below is a schematic of our home-built ion trapping instrument, combining laser vaporization synthesis with ion storage at cryogenic temperatures. Molecular ions produced in the source undergo free jet expansion, are mass-selected and injected into the 3 K ion trap. Here they are accumulated, buffer-gas cooled and subjected to laser radiation before the trap contents are extracted and analyzed by a quadrupole mass spectrometer and a Daly detector.

A remarkable aspect is the sensitivity that can be achieved by counting (almost) all mass-selected ions at the end of the trapping period. For example, it is possible to obtain spectroscopic data on just a few hundred stored ions, through what is referred to as ‘action spectroscopy’.

# LABORATORY

The hardware is contained within the series of high vacuum chambers shown below. Behind the instrument is an optical table where a variety of pulsed and continuous wave laser systems are installed.