Electron interactions with the heteronuclear carbonyl precursor H₂FeRu₃(CO)₁₃ and comparison with HFeCo₃(CO)₁₂: from fundamental gas phase and surface science studies to focused electron beam induced deposition

Abstract

In the current contribution we present a comprehensive study on the heteronuclear carbonyl complex H2FeRu3(CO)13 covering its low energy electron induced fragmentation in the gas phase through dissociative electron attachment (DEA) and dissociative ionization (DI), its decomposition when adsorbed on a surface under controlled ultrahigh vacuum (UHV) conditions and exposed to irradiation with 500 eV electrons, and its performance in focused electron beam induced deposition (FEBID) at room temperature under HV conditions. The performance of this precursor in FEBID is poor, resulting in maximum metal content of 26 atom % under optimized conditions. Furthermore, the Ru/Fe ratio in the FEBID deposit (≈3.5) is higher than the 3:1 ratio predicted. This is somewhat surprising as in recent FEBID studies on a structurally similar bimetallic precursor, HFeCo3(CO)12, metal contents of about 80 atom % is achievable on a routine basis and the deposits are found to maintain the initial Co/Fe ratio. Low temperature (≈213 K) surface science studies on thin films of H2FeRu3(CO)13 demonstrate that electron stimulated decomposition leads to significant CO desorption (average of 8–9 CO groups per molecule) to form partially decarbonylated intermediates. However, once formed these intermediates are largely unaffected by either further electron irradiation or annealing to room temperature, with a predicted metal content similar to what is observed in FEBID. Furthermore, gas phase experiments indicate formation of Fe(CO)4 from H2FeRu3(CO)13 upon low energy electron interaction. This fragment could desorb at room temperature under high vacuum conditions, which may explain the slight increase in the Ru/Fe ratio of deposits in FEBID. With the combination of gas phase experiments, surface science studies and actual FEBID experiments, we can offer new insights into the low energy electron induced decomposition of this precursor and how this is reflected in the relatively poor performance of H2FeRu3(CO)13 as compared to the structurally similar HFeCo3(CO)12.

Low Energy Electron- and Ion-Induced Surface Reactions of Fe(CO)5 Thin Films

“…Previous UHV surface science studies of the low energy electron-induced decomposition of adsorbed FEBID precursors have revealed that the first step in FEBID involves low energy electron-induced dissociation of the precursor, which is invariably accompanied by the desorption of one or more ligands from the precursor. − After this initial electron-induced ligand loss step, continued electron exposure typically causes ligand decomposition, rather than dissociation and desorption from the surface. ,− Thus, any ligands remaining on the surface after the initial ligand loss step are incorporated into the deposit. Reactions that accompany FIBID, however, are far less well-understood.…”

Magnetoelectrical Transport Improvements of Postgrowth Annealed Iron–Cobalt Nanocomposites: A Possible Route for Future Room-Temperature Spintronics

“…In this work, we extend this postgrowth protocol, based on annealing under high vacuum, to deposits obtained from a heteronuclear carbonyl HFeCo 3 (CO) 12 precursor, , to produce a metallic alloy with improved both electrical and magnetic properties. Our aim was to obtain granular material embedded in a carbon matrix and investigate its magnetotransport properties outperforming the ones with higher metal content.…”

Low-energy electron interaction and focused electron beam-induced deposition of molybdenum hexacarbonyl (Mo(CO)6)

“…Table 2 compares the relative contributions of individual ionic species observed in DEA and DI of Mo(CO) 6 . Similar to the approach in [55][56][57], the relative DEA contributions were obtained by integrating the negative ion yield over the whole width of individual contributions in the ion yield curves for each anionic fragment. These were then normalized to the [Mo(CO) 5 ] − contribution, which is set to 1.…”