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Imaging the He2 quantum halo state using a free electron laser
Stefan Zeller1, Maksim Kunitski2, Jörg Voigtsberger2
1Institut für Kernphysik, Goethe-Universität Frankfurt, 60438 Frankfurt, Germany; zeller@atom.uni-frankfurt.de doerner@atom.uni-frankfurt.de.
Summary
Researchers imaged a giant helium molecule, observing quantum tunneling where nuclei entered classically forbidden regions. This visualization confirmed the universal exponential decay of particle density in tunneling phenomena.
Area of Science:
- Quantum Mechanics
- Atomic and Molecular Physics
- Chemical Physics
Background:
- Quantum tunneling allows particles to traverse classically forbidden regions.
- Particle density typically decays exponentially in the tunneling region.
- This phenomenon is observed across various energy scales in nature.
Purpose of the Study:
- To investigate quantum tunneling in an extreme molecular system.
- To directly image the particle density within the tunneling region.
- To experimentally determine the binding energy of the helium molecule.
Main Methods:
- Utilized Coulomb explosion imaging.
- Employed a free electron laser for high-resolution imaging.
- Studied a unique, gigantic molecule composed of two helium atoms.
Main Results:
- Achieved direct imaging of exponentially decaying particle density over two orders of magnitude.
- Observed an 80% probability of helium nuclei being in the classically forbidden tunneling region.
- Determined the binding energy of the He₂ molecule to be [Formula: see text] neV.
Conclusions:
- Demonstrated a unique quantum system for visualizing universal tunneling behavior.
- Confirmed the exponential decay of particle density as a fundamental aspect of quantum tunneling.
- Provided experimental validation for theoretical calculations of He₂ binding energy.
