@article{RackwitzRankovićMilosavljevićetal.2017, author = {Rackwitz, Jenny and Ranković, Miloš Lj. and Milosavljević, Aleksandar R. and Bald, Ilko}, title = {A novel setup for the determination of absolute cross sections for low-energy electron induced strand breaks in oligonucleotides}, series = {The European physical journal : D, Atomic, molecular, optical and plasma physics}, volume = {71}, journal = {The European physical journal : D, Atomic, molecular, optical and plasma physics}, publisher = {Springer}, address = {New York}, issn = {1434-6060}, doi = {10.1140/epjd/e2016-70608-4}, pages = {9}, year = {2017}, abstract = {Low-energy electrons (LEEs) play an important role in DNA radiation damage. Here we present a method to quantify LEE induced strand breakage in well-defined oligonucleotide single strands in terms of absolute cross sections. An LEE irradiation setup covering electron energies <500 eV is constructed and optimized to irradiate DNA origami triangles carrying well-defined oligonucleotide target strands. Measurements are presented for 10.0 and 5.5 eV for different oligonucleotide targets. The determination of absolute strand break cross sections is performed by atomic force microscopy analysis. An accurate fluence determination ensures small margins of error of the determined absolute single strand break cross sections sigma SSB. In this way, the influence of sequence modification with the radiosensitive 5-Fluorouracil (U-5F) is studied using an absolute and relative data analysis. We demonstrate an increase in the strand break yields of U-5F containing oligonucleotides by a factor of 1.5 to 1.6 compared with non-modified oligonucleotide sequences when irradiated with 10 eV electrons.}, language = {en} } @article{SchuermannTitovEbeletal.2022, author = {Sch{\"u}rmann, Robin and Titov, Evgenii and Ebel, Kenny and Kogikoski Junior, Sergio and Mostafa, Amr and Saalfrank, Peter and Milosavljević, Aleksandar R. and Bald, Ilko}, title = {The electronic structure of the metal-organic interface of isolated ligand coated gold nanoparticles}, series = {Nanoscale Advances}, volume = {4}, journal = {Nanoscale Advances}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2516-0230}, doi = {10.1039/d1na00737h}, pages = {1599 -- 1607}, year = {2022}, abstract = {Light induced electron transfer reactions of molecules on the surface of noble metal nanoparticles (NPs) depend significantly on the electronic properties of the metal-organic interface. Hybridized metal-molecule states and dipoles at the interface alter the work function and facilitate or hinder electron transfer between the NPs and ligand. X-ray photoelectron spectroscopy (XPS) measurements of isolated AuNPs coated with thiolated ligands in a vacuum have been performed as a function of photon energy, and the depth dependent information of the metal-organic interface has been obtained. The role of surface dipoles in the XPS measurements of isolated ligand coated NPs is discussed and the binding energy of the Au 4f states is shifted by around 0.8 eV in the outer atomic layers of 4-nitrothiophenol coated AuNPs, facilitating electron transport towards the molecules. Moreover, the influence of the interface dipole depends significantly on the adsorbed ligand molecules. The present study paves the way towards the engineering of the electronic properties of the nanoparticle surface, which is of utmost importance for the application of plasmonic nanoparticles in the fields of heterogeneous catalysis and solar energy conversion.}, language = {en} }