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MO: Fachverband Molekülphysik

MO 4: Electronic Spectroscopy I

MO 4.6: Vortrag

Montag, 9. März 2020, 15:30–15:45, f142

High resolution laser induced Stark spectroscopy: Position dependent study on 3-, 4- and 5-Cyanoindole — •Marie-Luise Hebestreit, Hilda Lartian, and Michael Schmitt — Institute for Physical Chemistry I, Heinrich-Heine-University, Düsseldorf

In this contribution we present investigations of the electronic nature of 3-, 4- and 5-cyanoindole [1-3]. Indole and most of its derivatives have two close lying electronically excited singlet states labeled ¹L_a and ¹L_b in the nomenclature of Platt, which can be distinguished by the orientation of their transition dipole moment and by the magnitude and orientation of the permanent dipole moment [4,5]. In combination with ab initio calculations it is possible to determine the electronic nature for the lowest excited states via rotationally resolved Stark spectroscopy. The studies showed ¹L_a character for the lowest excited state of 4- and 5-cyanoindole, while for 3-cyanoindole the lowest excited state was determined to be an ¹L_b state. Reasons for this behavior are given by the influence of the inductive and mesomeric effect of the cyano group and the resulting electron density flow in the chromophor, depending if the cyano group is attached at the pyrrole ring or at the benzene ring.

[1] Schneider et al, Phys. Chem. Chem. Phys., 2018, 20, 23441

[2] Hebestreit et al, Phys. Chem. Chem. Phys., 2019, 21, 14766

[3] Wilke et al, Chem. Phys. Chem., 2016, 17, 2736.

[4] Platt, J. Chem. Phys., 1949, 17, 484.

[5] Weber, Biochem. J., 1960, 75, 335.