Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 99: Organic Molecules on Inorganic Substrates VI: Adsorption, Growth and Networks

O 99.7: Talk

Thursday, March 19, 2020, 12:15–12:30, GER 38

Electrospray Controlled Ion Beam Deposition as a powerful tool to deposit biomolecules on a solid support under UHV with subsequent STM imaging — •Karolina Stoiber, Andreas Walz, Peter Knecht, Anthoula Papageorgiou, Joachim Reichert, Annette Huettig, Hartmut Schlichting, and Johannes V. Barth — Physics E20, Technical University of Munich, Germany

Biomolecules gain interest in surface science and nanotechnology as potential building blocks in nano-sized structures or new materials. Their thermal fragility and lack of sublimation capacity make them ineligible for classical deposition technologies such as OMBE. Our new preparative approach based on electrospray ionization with controlled ion beam deposition (ES-CIBD) unlocks this potential. Data obtained with plasmid DNA, insulin and spermine are presented, representing three chemical classes (nucleic acids, proteins, polyamines) and molecular masses from 200 Da to 2 MDa. We applied negative and positive spray modes and tested different conformations introduced by variation of pH, ionic strength or by enzymatic manipulation. The ionization principle described by the charge residue model and chain ejection model is primarily determined by the outer shape of the molecule: here we experimentally compare globular and elongated forms. Parameters to evaluate the preparation process and quality of deposition are mass spectra to assess selectivity, ion currents for efficiency and imaging the deponents on Ag(111) and Cu(111) by UHV-STM for integrity. In conclusion, ES-CIBD is a versatile tool to selectively and efficiently deposit biomolecules on solid supports while the structure is preserved.