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A: Fachverband Atomphysik

A 13: Clusters II (joint session MO/A)

A 13.6: Vortrag

Dienstag, 10. März 2020, 15:15–15:30, f142

Investigation of isolated aggregates of coumarin derivatives in the gas phase by applying combined IR/UV spectroscopy — •Pol Boden, Anke Stamm, Michael Borchers, Dominic Bernhard, Dominique Maué, and Markus Gerhards — TU Kaiserslautern and State Research Center OPTIMAS, Germany

Coumarin and its derivatives are well known for their photo-induced reactivity leading to their importance as photobiological and photochemical substances. Here we report on 7-Hydroxy-4-methylcoumarin (7-H4MC) and its amino analogue 7-amino-4-methylcoumarin (7-A4MC). The examination of 7-A4MC is of great interest because aminocoumarins show an intramolecular charge-transfer (ICT) between the amino group and the benzopyrone unit in solvents of moderate to high polarity. In order to investigate intrinsic effects with respect to ICT and structure of the 7-A4MC dimer in the neutral and cationic ground states as well as in the S1 state, combined IR/UV spectroscopy is applied in molecular beam experiments. A comparison of the measured IR transitions with calculated frequencies and optimized structures allows clear structural assignments. Furthermore the 7H4MC dimer and its mono- and dihydrate are investigated both in their neutral and cationic ground state with regard to structural changes occuring upon UV photoionization. The tendencies of coumarins for self-aggregation observed in aqueous solution are investigated in detail on isolated species giving (in combination with hydration) a closer look on structure and function of coumarins.