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{Nanoa??gold, Iron (III)a??1,3,5a??benzene tricarboxylate Metal Organic Framework (MOF)} nanoa??composite as precursor for Laser Ablation Generation of golda??iron AumFen+/a?? (m = 1a??35, n=1a??5) clusters. Mass spectrometric study
摘要： Gold-iron bimetallic materials have applications in many fields, especially in nanotechnology and biomedicine. The chemistry of iron doped gold clusters is still not fully understood but opens up the possibility of developing new materials, e.g. of gold cages doped with iron atoms. There have been several theoretical studies on these clusters but only a few experimental studies. Laser desorption ionisation (LDI) was used for the generation of Au-Fe bimetallic clusters via laser ablation (337 nm nitrogen laser) of the synthesised nano-composite {nano-gold; Fe(III) 1,3,5-benzene tricarboxylate}, i.e. {AuNPs, Fe-MOF}, while a quadrupole ion trap time of flight mass spectrometer, equipped with a reflectron, was used to acquire mass spectra. A {AuNPs, Fe-MOF} nano-composite was prepared and found suitable for the LDI generation of AumFen clusters. In addition to Aum+/- (m = 1-35) clusters, a series of positively and negatively charged gold-iron AumFen+/- ones were generated. The mass spectra exhibited evidence for the clusters containing up to five iron atoms. In total, 113 binary AumFen+/- clusters (m = 1-35, n =1-5) were identified in the gas phase. A synthesised {AuNPs, Iron (III)-1,3,5-benzene tricarboxylate MOF} nano-composite was found suitable for the generation of many new gold-iron clusters and mass spectrometry was shown to be an efficient technique for the determination of the cluster stoichiometry. A broad series of over 100 bimetallic AumFen clusters, some of them suggested to be gold cages doped with iron atoms (for m = 12 and higher), not only demonstrate a rich and complex chemistry, but also open wide possibilities of biomedical applications.
关键词： nanoparticles,Mass spectrometry,MOF,Gold-iron,Laser desorption ionisation,Clusters,Nano-composite
更新于2025-09-19 17:13:59
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Bragg coherent diffraction imaging of iron diffusion into gold nanocrystals
摘要： Understanding how diffusion takes place within nanocrystals is of great importance for their stability and for controlling their synthesis. In this study, we used the strain sensitivity of Bragg coherent diffraction imaging (BCDI) to study the diffusion of iron into individual gold nanocrystals in situ at elevated temperatures. The BCDI experiments were performed at the I-07 beamline at Diamond Light Source, UK. The diffraction pattern of individual gold nanocrystals was measured around the (11-1) Bragg peak of gold before and after iron deposition as a function of temperature and time. Phase retrieval algorithms were used to obtain real space reconstructions of the nanocrystals from their measured diffraction patterns. Alloying of iron with gold at sample temperatures of 300 °C–500 °C and dealloying of iron from gold at 600 °C were observed. The volume of the alloyed region in the nanocrystals was found to increase with the dose of iron. However, no significant time dependence was observed for the structure following each iron deposition, suggesting that the samples reached equilibrium relatively quickly. The resulting phase distribution within the gold nanocrystals after the iron depositions suggests a contraction due to diffusion of iron. Our results show that BCDI is a useful technique for studying diffusion in three dimensions and alloying behaviour in individual crystalline grains.
关键词： gold iron,nanocrystals,diffusion,Bragg coherent diffraction imaging
更新于2025-09-09 09:28:46