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Updated: May 2, 2026
All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
Femtosecond Real-Time Observation of Tunneling Autodetachment from Dipole-Bound States Reveals Structural Dynamics of
Dabin Kim1, Sejun An1, Sang Kyu Kim1
1Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
Abstract:
Femtosecond time-resolved photoelectron spectroscopy combined with ab initio electronic structure and molecular dynamics calculations reveals the real-time structural and electronic evolution of sodium halide dimers, (NaCl)2 and (NaI)2, following vertical electron detachment from their corresponding anions. Both pseudo-linear dimer anions transform into rhombic neutral geometries upon electron detachment. Despite the weak binding of the excess electron, the dipole-bound state (DBS) of each anion temporarily traps the electron within a finite potential well, creating a tunneling barrier that governs autodetachment. The estimated lifetimes of DBS are ∼4 ps for (NaCl)2- and ∼40 ps for (NaI)2-, in excellent agreement with theoretical tunneling barrier heights of ∼50 and ∼100 meV, respectively. These results constitute the first direct experimental observation of tunneling autodetachment from a DBS and demonstrate how femtosecond structural relaxation of the neutral core drives quantum mechanical electron decay.
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