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Updated: Oct 14, 2025

Spatial Separation of Molecular Conformers and Clusters
Published on: January 9, 2014
Observation and Exploitation of Spin-Orbit Excited Dipole-Bound States in Ion-Molecule Clusters
Wenjin Cao1, Hanhui Zhang1,2, Qinqin Yuan1
1Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
Abstract:
We report an observation of spin-orbit excited dipole-bound states (DBSs) in arginine-iodide complexes (Arg·I-) by using temperature-dependent, wavelength-resolved "iodide-tagging" negative ion photoelectron spectroscopy. The observed DBSs are bound to the spin-orbit excited I(2P1/2) level of the neutral Arg·I complex in zwitterionic conformations and identified based on the resonant enhancement due to spin-orbit electronic autodetachment from the I(2P1/2) DBS to the I(2P3/2) neutral ground state. The observed DBS binding energies are correlated to the dipole moments of neutral Arg·I isomers and tautomers. This work thus demonstrates a new and generic spectroscopic approach to identify ion-molecule cluster conformations based on their distinguishable dipole moments.
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