Traditionally, silicon detectors, utilized in the field of studying the chemical properties of superheavy elements, are coated with gold. However, enhanced reactivity of element 113, Nh, towards gold disabled the proper chemical characterization of this element. Therefore, a need for new chemically modified gold-coated silicon detectors that will selectively bind the atoms of interest, but with weaker interactions, has emerged. Meitnerium is expected to be a member of Group 9 of the periodic table, and a brand new chemical research is needed to confirm this classification. Initially, we aimed to study the self-assembly of a commercially available thiol, 1-(11-Mercaptoundecyl)imidazole, on gold-coated silicon chips that mimic functionalized detectors. The main goal of such devices is to capture radioactive isotopes of iridium and rhodium (meitnerium’s homologs) during online Cyclotron-based experiments. Self-assembled monolayers (SAMs) can be easily prepared in the liquid phase by immersion of a substrate into an ethanolic thiol solution. Several techniques were used to characterize the functionalized chips. Atomic force microscopy was used to evaluate the roughness of pure gold and substrates with self-assembled monolayers (SAMs). We obtained satisfactory results on the average surface coverage with SAMs (≥ 90%) using cluster secondary-ion mass spectrometry. X-ray photoelectron spectroscopy was employed to study the chemical state of SAMs. The H2O2-mediated liquid UV-light photooxidation was found to be an effective treatment to remove SAMs. Ellipsometry was used to determine the thickness of SAMs, which indicated the presence of a single monolayer. Finally, neutron activation analysis was performed to conclude that iridium and rhodium bind to SAMs on gold from hydrochloric acid solutions (sorption efficiency ≥ 55%). Details and results of the experiments mentioned above will be discussed.

Characterization of 1-(11-Mercaptoundecyl)imidazole self-assembled monolayers on gold-coated silicon chips for future detection of radioactive isotopes

ACS Spring Meeting 2021

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