Interatomic relaxation processes induced in neon dimers by electron-impact ionization

We report an experimental observation of the interatomic Coulombic decay (ICD) and radiative charge-transfer (RCT) processes in a Ne dimer $\left(e,2e\right)$ following a 380-eV electron impact. By detecting the $\mathrm{N}{\mathrm{e}}^{+}-\mathrm{N}{\mathrm{e}}^{+}$ cation pair and one of the emitted electrons in coincidence, the fingerprint of the ICD process initiated by the inner-valence ionization of Ne is obtained. Furthermore, the experimental results and ab initio calculations together unambiguously confirm the occurrence of the RCT process, and we show that most of the low-energy electrons produced in ionization of the Ne dimers are due to the ICD, which strongly suggests the importance of the ICD in causing radiation damage in a biological medium.

Figure 1

(a) The KER corresponding to a $\mathrm{N}{\mathrm{e}}^{+}/\mathrm{N}{\mathrm{e}}^{+}$ ion pair. The black dots: experimental results and the red curve: ab initio calculation results. (b) (The red dots) Electron energy distribution corresponding to the low-energy KER peak of a $\mathrm{N}{\mathrm{e}}^{+}/\mathrm{N}{\mathrm{e}}^{+}$ ion pair (3–6 eV) and (the blue triangles, lines) electron energy distribution corresponding to the single ionization of a Ne atom.

Figure 2

A correlation map between the electron energy and the KER. The black dashed line: the position of the ICD initial $\mathrm{N}{\mathrm{e}}^{+}\left(2s2p^6\right)-\mathrm{Ne}\left(2p^6\right)$ states, see the text for details; the red dashed rectangle: the electron from the single ionization of $\mathrm{N}{\mathrm{e}}_2$ followed by the ICD and the electrons from the two-site double ionization and the red solid rectangle: electrons from the RCT process.