Slow Interatomic Coulombic Decay of Multiply Excited Neon Clusters

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Materials Science

Background:

• Neon clusters (Ne) are model systems for studying excited-state dynamics.
• Free electron lasers (FELs) provide intense, tunable radiation for probing atomic and molecular systems.
• Interatomic or intermolecular Coulombic decay (ICD) is a key non-radiative decay pathway in excited atomic and molecular systems.

Purpose of the Study:

• To investigate the non-radiative decay mechanisms of multiply excited neon clusters.
• To understand the role of the cluster environment on interatomic Coulombic decay (ICD) dynamics.
• To explore the influence of free electron laser (FEL) intensity on cluster excitation and decay rates.

Main Methods:

• Resonant excitation of Ne clusters (∼5000 atoms) using seeded FEL radiation at FERMI.
• Probing specific sites within the clusters due to precise FEL tunability and narrow bandwidth.
• Analysis of decay pathways, including interatomic/intermolecular Coulombic decay (ICD) and inelastic electron scattering.

Main Results:

• Cluster surface atom relaxation occurs via sequential ICD processes.
• Bulk atom ICD is influenced by the surrounding excited medium through inelastic electron scattering.
• Cluster excitations relax to atomic states before ICD, indicating a slow decay process (picosecond range).
• FEL intensity controls the average number of excitations per cluster, enabling coarse tuning of the ICD rate.

Conclusions:

• The study elucidates the complex decay dynamics of excited neon clusters.
• ICD in neon clusters is a slow, environmentally dependent process.
• FEL intensity offers a means to control non-radiative decay rates in atomic clusters.