Radiative Cooling Dynamics of Molecules
(Otto Hahn Group)

Our group is working on the development of new experimental methods to study the spontaneous emission of molecules using time-resolved and dispersed fluorescence spectroscopy on extended timescales.

We plan to study the emission of light in the visible and infrared range on extended timescales up to micro- and milliseconds with quantum state resolution. Molecular fluorescence on these rather long timescales can lead to significant radiative cooling under conditions where collisions and other energy dissipation channels are less important. It is this regime that we want to reproduce in the laboratory, for example by isolating molecular ions in ion traps, to obtain information on the intramolecular cooling dynamics in the form of fluorescence lifetimes and dispersed emission spectra.

Radiative cooling of molecules in the interstellar medium

Molecules that exist in cold and less dense regions of the interstellar medium (ISM) are of particular interest. These include carbon-rich species, such as polycyclic aromatic hydrocarbons (PAHs), carbon chains and fullerenes, as well as other small molecules. Under the extreme conditions of the ISM, radiative cooling can play a direct role in stabilizing reaction products and the associated emission spectra can be used to identify molecules in interstellar space.

Experimental techniques

To achieve the necessary sensitivity for such experiments, we combine several (often custom-made) experimental tools: including pulsed ion beam sources, cryogenic ion traps, ultra-high vacuum, tunable pulsed lasers, and single-photon detectors for the visible and infrared.