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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Temporal stability of magic-number metal clusters: beyond the shell closing model
Anil Desireddy1, Santosh Kumar, Jingshu Guo
1Department of Chemistry, The University of Toledo, Toledo, OH 43606, USA.
Nanoscale
|February 2, 2013
Summary
Magic-number metal clusters, like silver:glutathione (Ag:SG), exhibit unique stability but can decay. Understanding their decay and stabilization is key for theory and technology development.
Area of Science:
- Nanomaterials Science
- Physical Chemistry
- Surface Chemistry
Background:
- Magic-number metal clusters possess anomalous stability due to closed geometric and electronic shells.
- Despite inherent stability, these clusters can decay in condensed phases, complicating research and applications.
- Controlling cluster instability is crucial for advancing cluster stability theory and enabling technological development.
Purpose of the Study:
- To investigate the solution phase stability of silver:glutathione (Ag:SG) clusters.
- To elucidate the decay mechanisms of magic-number metal clusters.
- To identify strategies for controlling cluster stability.
Main Methods:
- Studied Ag:SG cluster stability across varying sizes, pH, and chemical environments.
- Utilized electrophoretic separations to analyze cluster decay products and mass redistribution.
- Employed optical absorption spectroscopy to track cluster evolution and identify stable sizes.
Main Results:
- Cluster stability showed a non-monotonic dependence on size.
- Dominant decay mechanism involved mass redistribution towards smaller, known cluster sizes.
- Smaller clusters evolved towards two predominant stable cluster sizes.
- Net surface charge significantly influenced cluster stabilization, but charge screening did not, contrary to DLVO theory.
- Decay involved the loss of Ag(+) ions and silver glutathionates.
- Clusters were stabilized by Ag(+) addition and destabilized by glutathione addition or Ag(+) removal.
- Optimal stability was observed near neutral pH, correlating with a net negative surface charge.
Conclusions:
- Silver:glutathione clusters exhibit size-dependent stability and specific decay pathways.
- Surface charge plays a critical role in cluster stabilization.
- Strategies like controlling Ag(+) ion concentration and pH can manage cluster stability and decay.
- These findings offer mechanistic insights for designing and synthesizing specific magic-number metal cluster species.
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