Nanocomposites and Nanomaterials

Witnessing emergence of order in thermally reconfigurable plasmonic superlattices by in-situ electron tomography

M.Bagiński1, M.Tupikowska1, W.Lewandowski1
1 Faculty of Chemistry, University of Warsaw. Pasteura 1 Street, 02-093 Warsaw, Poland. 
E-mail: mbaginski@chem.uw.edu.pl

       Understanding the crystallization of photonic nanomaterials is of paramount importance for their emerging properties. With that, it has direct impact on the development of future optoelectronic technologies that rely on such materials [1].       While crystallization in a solvated environment has already been studied using ex-situ methods, the crystallization in solid-state, reconfigurable assemblies of nanoparticles (NPs) remained so far unexplored. 
         To fill this gap, in this work, we present proof-of-principle experiments on crystallization of thermally reconfigurable assemblies of NPs, which is an excellent testing material [2] enabling investigation with in-situ and ex-situ measurement techniques. The unique application of TEM tomography combined with in-situ thermal control, and correlation of the results of different methods, enabled us to understand the impact of various conditions on the crystallization process. Ensemble measurements with SAXRD highlighted the dependence of the correlation length in the NPs assemblies on the number of heating/cooling cycles and the rate of cooling. In-situ TEM tomography revealed unique, single particle level information on the 3D positional order evolution within assemblies. The structural information on assemblies crystallized in different conditions was used as the basis for modelling of their plasmonic properties, revealing the origin of the experimentally observed differences in measured extinction spectra of the different crystalline phases. 

1. M. Kovalenko, et al., ACS Nano, 9 (2), 1012–1057 (2015).
2.M. Baginski et al., Chemistry of Materials, 30 (22), 8201-8210 (2018).