Hannover 2020 – scientific programme

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MO: Fachverband Molekülphysik

MO 6: Electronic Spectroscopy II

MO 6.2: Talk

Tuesday, March 10, 2020, 14:15–14:30, f102

Determination of dipole moments in the electronically excited state of different constitutional isomers of cyanoindole via thermochromic methods — •Matthias Zajonz, Mirko Lindic, and Michael Schmitt — Institute for Physical Chemistry I, Heinrich-Heine-University, Düsseldorf

In this contribution we present the determination of dipole moments in the electronically excited state of different cyanoindoles via thermochromic methods. These methods were introduced by Gryczynski and Kawski due to their advantages over solvatochromic methods [1]. Their basic advantage is that the combination of solvent and solute is kept constant and the required variation of the permittivity ε and index of refraction n to generate spectroscopic shifts of the absorption and emission spectra is mediated through temperature changes. Our goal is to improve the methods of dipole moment determination in solution via thermochromic methods, since the superior Stark spectroscopy in the gas phase is not feasible for all molecules. In addition, investigations are carried out to better understand the temperature dependence of the variables ε, n and the cavity volume, which replaces the inaccurate Onsager-Radius in thermochromic equations [2]. Cyanoindoles were selected because they can be measured in gas phase using Stark spectroscopy within the research group [3], so values can be compared with gas phase values and ab initio calculations as well.

[1] Gryczynski et al, Zeit. f. Nat., 1975, 30

[2] Lindic et al, Spec. Acta Part A, 2019, in press

[3] Schneider et al, Phys. Chem. Chem. Phys., 2018, 20