Recently Cederbaum et al. [Phys. Rev. Lett. 79, 4778 (1997)] predicted a new decay channel of excited atoms and molecules termed interatomic Coulombic decay (ICD). In ICD the deexcitation energy is transferred via virtual photon exchange to a neighboring atom, which releases it by electron emission. We report on an experimental observation of ICD in $2s$ ionized neon dimers. The process is unambiguously identified by detecting the energy of two ${\mathrm{N}\mathrm{e}}^{1+}$ fragments and the ICD electron in coincidence, yielding a clean, background free experimental spectral distribution of the ICD electrons.

• Received 6 May 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.163401