Decomposition of Iron Pentacarbonyl Induced by Singly and Multiply Charged Ions and Implications for Focused Ion Beam-Induced Deposition

Focused ion beams are becoming important tools in nanofabrication. The underlying physical processes in the substrate were already explored for several projectile ions. However, studies of ion interaction with precursor molecules for beam-assisted deposition are almost nonexistent. Here, we explore the interaction of various projectile ions with iron pentacarbonyl. We report fragmentation patterns of isolated gas-phase iron pentacarbonyl after interaction with He-4(+) at a collision energy of 16 keV, He-4(2+) at 16 keV, Ne-20(+) at 6 keV, Ne-20(4+) at 40 keV, Ar-40(+) at 3 keV, Ar-40(3+) at 21 keV, Kr-84(3+) at 12 keV, and Kr-84(17+) at 255 keV. These projectiles cover interaction regimes ranging from collisions dominated by nuclear stopping through collisions dominated by electronic stopping to soft resonant electron-capture interactions. We report a surprising efficiency of Ne+ in the Fe(CO)(5) decomposition. The interaction with multiply charged ions results in a higher content of parent ions and slow metastable fragmentation due to the electron-capture process. The release of CO groups during the decomposition process seems to take off a significant amount of energy. The fragmentation mechanism may be described as Fe being trapped within a CO cluster.