Role Of Nh3 In The Electron-Induced Reactions Of Adsorbed And Solid Cisplatin

The electron-induced decomposition of cisplatin (cis-Pt(NH3)(2)Cl-2) was investigated to reveal if ammine (NH3) ligands have a favorable effect on the purity of deposits produced from metal-containing precursor molecules by focused electron beam induced deposition (FEBID). Scanning electron microscopy showed that cisplatin particles of different sizes react violently during electron irradiation. In particular, faceted particles of a few mu m in size started to boil, became spherical and subsequently degraded. Energy-dispersive X-ray spectroscopy gave evidence for the formation of nearly pure platinum and a decrease of the chlorine content. Nitrogen, however, was not detected, pointing to an efficient and rapid removal of NH3. In contrast, PtCl2 particles do not degrade under comparable conditions, demonstrating that the ammine ligand plays an important role in the reduction of cisplatin to pure platinum. The fast release of NH3 ligands under electron exposure was confirmed by high resolution electron energy loss spectroscopy, focusing in particular on low-energy electrons as produced in high amounts during the FEBID process. Finally, FEBID experiments using cisplatin adsorbed from the gas phase onto a surface produced amorphous deposits. In contrast to the decomposed cisplatin particles, these deposits had a chlorine content of about 50 at. %. Only after extensive irradiation in a transmission electron microscope was this chlorine content reduced and were crystalline particles obtained. In conclusion, using NH3 as ligand in metal containing FEBID precursors can favor the formation of pure metal deposits, but its effectiveness depends on the precise experimental conditions.