Related Experiment Video
Updated: Jul 6, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Metastable feshbach molecules in high rotational states
1Institut für Experimentalphysik and Forschungszentrum für Quantenphysik, Universität Innsbruck, 6020 Innsbruck, Austria.
Physical Review Letters
|March 21, 2008
Summary
We created ultracold cesium molecules (Cs2) that are stable for 1 second, even above their dissociation energy. This breakthrough in quantum physics allows for controlled molecule dissociation on demand.
Area of Science:
- Atomic, Molecular, and Optical (AMO) Physics
- Quantum Chemistry
- Ultracold Quantum Gases
Background:
- Feshbach molecules are crucial for controlling ultracold atomic gases.
- Understanding molecular stability near the dissociation threshold is key for quantum applications.
Purpose of the Study:
- To experimentally demonstrate stable Cs2 Feshbach molecules above the dissociation threshold.
- To investigate the mechanism of metastability and controlled dissociation.
Main Methods:
- Preparation of optically trapped ultracold Cs2 dimers in high rotational states.
- Magnetic field tuning into a region of negative binding energy.
- Observation of molecular stability and controlled dissociation dynamics.
Main Results:
- Demonstrated Cs2 Feshbach molecules stable for 1 second, well above dissociation.
- Identified metastability due to centrifugal barrier and suppressed coupling to low rotational states.
- Observed sharp, magnetically controlled dissociation onset.
Conclusions:
- Metastable Feshbach molecules can exist above the dissociation threshold.
- Centrifugal barriers play a critical role in stabilizing these molecules.
- Controlled dissociation on demand is achievable with well-defined energy.
Related Concept Videos
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
03:51Molecular Orbital Theory II
Molecular Orbital Energy Diagrams
01:14Molecular Spectroscopy: Absorption and Emission
Molecules possess discrete energy levels called quantum states. Unlike atoms, which have simpler energy levels, molecules possess additional rotational and vibrational energy levels. Each energy level is separated by an energy gap, with the gaps between adjacent electronic, vibrational, and rotational levels varying significantly. The three types of energy levels in a diatomic molecule are shown in Figure 1.
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:14Atomic Nuclei: Nuclear Spin State Population Distribution
Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
01:25Deactivation Processes: Jablonski Diagram
Luminescence, the emission of light by a substance that has absorbed energy, is a process that involves the interaction of molecules with light. The energy-level diagram, or Jablonski diagram, is a graphical representation of these interactions, illustrating the various states and transitions a molecule can undergo. In a typical Jablonski diagram, the lowest horizontal line represents the ground-state energy of the molecule, which is usually a singlet state. This state represents the energies...