Understanding energy relaxation dynamics in weakly bound systems following excitation is fundamental to diverse phenomena, from radiation-induced biological damage to interstellar chemistry. Here, we investigate the photoinduced fragmentation dynamics of both isolated ${\mathrm{N}}_2\mathrm{O}$ molecules and their molecular clusters using a broadband extreme ultraviolet light source. Beyond direct photoionization processes, we observe indirect ionization pathways that generate low-energy electrons (LEEs) in the 0–10 eV range. This process originates from the population of neutral superexcited states in ${\mathrm{N}}_2\mathrm{O}$, followed by either intramolecular autoionization or resonant intermolecular Coulombic decay. In large clusters, we observe a remarkable enhancement of LEE production, with yields becoming comparable to those from direct ionization. Additionally, among all fragmentation products correlated with indirect LEEs, the ionic fragments containing ${\mathrm{N}}^{+}$ and ${\mathrm{O}}^{+}$ are significantly reduced, which is in contrast to the situation for isolated ${\mathrm{N}}_2\mathrm{O}$ molecules. Our observations demonstrate that the decay of superexcited states is significantly influenced by the molecular cluster environment and may extend to the radiation-induced biological damage processes.

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• Atomic & molecular clusters
• Atomic & molecular collisions
• Autoionization & Auger processes
• Electronic excitation & ionization
• Laser-cluster interaction
• Single- and few-photon ionization & excitation