Electron Microscopic Observation of an Icosahedral Au13 Core in Au25(SePh)18 and Reversible Isomerization between Icosahedral and Face-Centered Cubic Cores in Au144(SC2H4Ph)60
journal contributionposted on 05.03.2020, 20:43 by Ryo Takahata, Seiji Yamazoe, Yosuke Maehara, Kenji Yamazaki, Shinjiro Takano, Wataru Kurashige, Yuichi Negishi, Kazutoshi Gohara, Tatsuya Tsukuda
The atomic structures of Au25(SC2H4Ph)18, Au25(SePh)18, and Au144(SC2H4Ph)60, for which the crystal structures have been solved, were examined by aberration-corrected transmission electron microscopy (ACTEM). Time-lapse ACTEM images of Au25(SePh)18 exhibited characteristic patterns for the Ih Au13 core more frequently compared to Au25(SC2H4Ph)18 at a dose rate (DR) = 4 pA/cm2. In contrast, time-lapse images of Au144(SC2H4Ph)60 randomly showed two types of patterns for the Ih and fcc cores at DR = 4 pA/cm2, indicating that Au144(SC2H4Ph)60 can be interconverted between the two isomeric forms without fragmentation. We proposed that the Ih isomer is more stable than the fcc isomer in Au144(SC2H4Ph)60 based on population analysis of the images of individual isomers.