Imaging the He-2 quantum halo state using a free electron laser
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Authors
Zeller, Stefan
Kunitski, Maksim
Voigtsberger, Joerg
Kalinin, Anton
Schottelius, Alexander
Schober, Carl
Waitz, Markus
Sann, Hendrik
Hartung, Alexander
Bauer, Tobias
Issue Date
2016
Type
Article
Language
Keywords
clusters , helium dimer , wavefunction , tunneling
Alternative Title
Abstract
Quantum tunneling is a ubiquitous phenomenon in nature and crucial for many technological applications. It allows quantum particles to reach regions in space which are energetically not accessible according to classical mechanics. In this "tunneling region," the particle density is known to decay exponentially. This behavior is universal across all energy scales from nuclear physics to chemistry and solid state systems. Although typically only a small fraction of a particle wavefunction extends into the tunneling region, we present here an extreme quantum system: a gigantic molecule consisting of two helium atoms, with an 80% probability that its two nuclei will be found in this classical forbidden region. This circumstance allows us to directly image the exponentially decaying density of a tunneling particle, which we achieved for over two orders of magnitude. Imaging a tunneling particle shows one of the few features of our world that is truly universal: the probability to find one of the constituents of bound matter far away is never zero but decreases exponentially. The results were obtained by Coulomb explosion imaging using a free electron laser and furthermore yielded He-2's binding energy of 151.9 +/- 13.3 neV, which is in agreement with most recent calculations.
Description
Citation
Zeller, S., Kunitski, M., Voigtsberger, J., Kalinin, A., Schottelius, A., Schober, C., ... & Pitzer, M. (2016). Imaging the He2 quantum halo state using a free electron laser. Proceedings of the National Academy of Sciences, 113(51), 14651-14655.
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License
In Copyright (All Rights Reserved)
Journal
Volume
Issue
PubMed ID
ISSN
0027-8424