P Ragesh Kumar T, Weirich Paul, Hrachowina Lukas, Hanefeld Marc, Bjornsson Ragnar, Hrodmarsson Helgi Rafn, Barth Sven, Fairbrother D Howard, Huth Michael, Ingólfsson Oddur
Science Institute and Department of Chemistry, University of Iceland, Reykjavík, Iceland.
Physikalisches Institut, Max-von-Laue-Str. 1, Goethe-Universität, 60438 Frankfurt am Main, Germany.
Beilstein J Nanotechnol. 2018 Feb 14;9:555-579. doi: 10.3762/bjnano.9.53. eCollection 2018.
In the current contribution we present a comprehensive study on the heteronuclear carbonyl complex HFeRu(CO) 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, HFeCo(CO), 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 HFeRu(CO) 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) from HFeRu(CO) 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 HFeRu(CO) as compared to the structurally similar HFeCo(CO).
在本论文中，我们对异核羰基配合物HFeRu(CO)进行了全面研究，内容涵盖其在气相中通过解离电子附着（DEA）和解离电离（DI）产生的低能电子诱导碎片化过程、在超高真空（UHV）可控条件下吸附于表面并暴露于500 eV电子辐照时的分解情况，以及在高电压（HV）条件下室温聚焦电子束诱导沉积（FEBID）中的性能表现。该前驱体在FEBID中的性能较差，在优化条件下金属含量最高仅为26原子%。此外，FEBID沉积物中的Ru/Fe比（约为3.5）高于预测的3:1比例。这有点令人惊讶，因为在最近对结构相似的双金属前驱体HFeCo(CO)的FEBID研究中，通常可实现约80原子%的金属含量，且发现沉积物能保持初始的Co/Fe比。对HFeRu(CO)薄膜进行的低温（约213 K）表面科学研究表明，电子激发分解会导致大量CO脱附（每个分子平均有8 - 9个CO基团），形成部分脱羰中间体。然而，一旦形成，这些中间体在很大程度上不受进一步电子辐照或升温至室温的影响，预测的金属含量与FEBID中观察到的相似。此外，气相实验表明，低能电子作用于HFeRu(CO)时会形成Fe(CO)。该碎片在高真空条件下可在室温脱附，这可能解释了FEBID沉积物中Ru/Fe比略有增加的原因。通过气相实验、表面科学研究和实际FEBID实验相结合，我们能够对该前驱体的低能电子诱导分解以及与结构相似的HFeCo(CO)相比HFeRu(CO)性能相对较差的原因提供新的见解。
