Fission of Polyanionic Metal Clusters.

Area of Science:

• Atomic and Molecular Physics
• Condensed Matter Physics
• Materials Science

Background:

• Dianionic metal clusters typically display limited decay channels.
• Lead clusters present an opportunity to study size-dependent electronic transitions.

Purpose of the Study:

• Investigate the photoexcitation decay pathways of size-selected dianionic lead clusters (Pb_{n}^{2-}).
• Determine the dominant decay processes and their dependence on cluster size.
• Identify potential signatures of electronic transitions within lead clusters.

Main Methods:

• Size-selected dianionic lead clusters (Pb_{n}^{2-}, n=34-56) were confined in a Penning trap.
• Photoexcitation was used to induce cluster decay.
• Mass spectrometry was employed to analyze fragment ions and compare with monoanionic precursors.

Main Results:

• Lead clusters displayed diverse decay channels, unlike other dianionic metal clusters.
• The fission reaction Pb_{n}^{2-}→Pb_{n-10}^{-}+Pb_{10}^{-} was the primary decay pathway for clusters with n < 48.
• This fission process diminished for larger cluster sizes, hinting at a nonmetal-to-metal transition.

Conclusions:

• The Pb_{10}^{-} and Pb_{n-10}^{-} fragment pair serves as a fingerprint for dianionic lead cluster decay.
• This observation allowed tracing dianionic clusters down to Pb_{21}^{2-}.
• The disappearance of fission decay suggests a size-induced transition from a nonmetallic to a metallic state in lead clusters.