Dresden 2026 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: Emerging Topics in Chemical and Polymer Physics, New Instruments and Methods II

CPP 15.5: Vortrag

Montag, 9. März 2026, 18:15–18:30, ZEU/0255

The Power of One Oxygen: How a Single Atom Alters the Field Evaporation of Liquid Crystals — •Kuan Meng, Sebastian Eich, and Guido Schmitz — University of Stuttgart, Institute for Materials Science, Heisenbergstr. 3, 70569 Stuttgart, Germany

In this study, we established a cryo-atom probe tomography (cryo-APT) workflow to investigate how the presence of a single oxygen atom alters the field evaporation behavior of two structurally similar liquid crystals: 8CB and 8OCB. Both compounds exhibited over 70% intact molecular retention and comparable fragmentation patterns.

Mass spectra revealed that the oxygen in 8OCB hinders the formation of extended cyanobiphenyl fragments across the linkage and promotes full cleavage of the alkyl chain. In contrast, 8CB allows the formation of longer backbone fragments. Spatially, 8CB evaporated mainly as intact molecules across both crystalline and smectic domains. 8OCB, however, evaporated predominantly as small fragments in low volume-density domains while as larger fragments or intact molecules in the high volume-density regions, which are suspected to crystalline and smectic phases, respectively. Further structural validation is required.

This work illustrates how cryo-APT enables the characterization of the molecular structure of organic liquid systems and demonstrates that even a single oxygen atom can fundamentally alter their field evaporation pathways. It further proposes a tunable fragmentation strategy to investigate molecular orientation in soft matter at an unprecedented resolution.

Keywords: Cryo Atom Probe Tomography; Liquid Crystals; Field evaporation; Molecular Liquids; Nanoscale Structure