Unraveling the Metastability of Cn2+ (n = 2–4) Clusters

摘要: Pure carbon clusters have received considerable attention for a long time. However, fundamental questions, such as what the smallest stable cluster dication is, remain unclear. We investigated stability and fragmentation behavior of Cn2+ (n = 2–4) dications using state-of-the-art atom probe tomography. These small doubly charged ions were produced by laser-pulsed field evaporation from tungsten carbide emitter. Correlation analysis fragments detected in coincidence reveals that they only decay to Cn–1+ + C+. During C22+ → C+ C+, significant kinetic energy release (∼5.75–7.8 eV) is evidenced. Through advanced experimental data processing combined with ab initio calculations simulations, we show field-evaporated diatomic 12C22+ are either weakly bound 3Πu 3Σg– states, quickly dissociating under intense electric field, or deeply electronic 5Σu– state lifetimes >180 ps.