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MO: Fachverband Molekülphysik

MO 14: Photochemistry II

MO 14.5: Vortrag

Mittwoch, 16. März 2022, 15:30–15:45, MO-H6

Accurate determination of the Adenine-Thymine binding energy — •Sebastian Hartweg¹, Majdi Hochlaf², Gustavo Garcia³, and Laurent Nahon³ — ¹Albert-Ludwigs-Universität Freiburg, Deutschland — ²Université Gustave Eiffel, Champs-sur-Marne, Frankreich — ³Synchrotron SOLEIL, St-Aubin, Frankreich

Among the many intermolecular interactions known between biomolecules, the hydrogen bonding between the nucleobases Adenine (A) and Thymine (T) as well as between Guanine and Cytosine take a special place since they shape the DNA double strand structure. The strength of these hydrogen-bond interactions, at the center of the genetic code, is thus of significant interest for radiobiology.

We will present a study of the single photon ionization of gas phase A and T molecules and their dimers AA, AT and TT using double imaging photoelectron photoion coincidence (i2PEPICO) spectroscopy performed at the VUV beamline DESIRS of the French SOLEIL synchrotron. By evaluating the threshold photoelectron spectra (TPES) and photon energy-dependent ion kinetic energy release data we determined the threshold for photoionization and dissociative photoionization of the different clusters. By comparison with high-level ab initio calculations dealing with neutral and ionic species, we can relate the determined quantities to the binding energy of the neutral AT pair. The favorable comparison between theory and experimental results gives further credibility in theoretical predictions for similar systems.