Related Experiment Video
Updated: Jun 14, 2026
09:49
An Experimental Protocol for Femtosecond NIR/UV - XUV Pump-Probe Experiments with Free-Electron Lasers
Published on: October 23, 2018
Broad Feshbach resonance in the 6Li-40K mixture
T G Tiecke1, M R Goosen, A Ludewig
1van der Waals-Zeeman Institute of the University of Amsterdam, Valckenierstraat 65, 1018 XE, The Netherlands.
Physical Review Letters
|April 7, 2010
Summary
Researchers studied Feshbach resonances in ultracold atomic mixtures of lithium-6 and potassium-40. They experimentally determined the resonance width, crucial for exploring universal physics in mass-imbalanced fermionic gases.
Area of Science:
- Atomic, Molecular, and Optical Physics
- Quantum Gases
- Ultracold Atomic Systems
Background:
- Feshbach resonances are crucial for controlling interactions in ultracold atomic gases.
- Understanding interspecies Feshbach resonances is key for creating and manipulating mixtures of different atomic species.
- Mass-imbalanced fermionic mixtures present unique opportunities for studying quantum phenomena.
Purpose of the Study:
- To develop a theoretical model for calculating Feshbach resonance properties in atomic mixtures.
- To experimentally determine the width of an interspecies Feshbach resonance in a 6Li/40K mixture.
- To assess the potential of the 6Li/40K system for observing universal crossover physics.
Main Methods:
- Development of a theoretical model to predict Feshbach resonance positions and widths.
- Experimental measurement of the 6Li atom distillation rate in a 6Li/40K mixture as a function of magnetic field.
- Analysis of the asymmetric Fano line shape of the interspecies elastic cross section.
Main Results:
- A model for calculating Feshbach resonance properties was successfully developed.
- The first experimental determination of the width of an interspecies Feshbach resonance in the 6Li/40K mixture was achieved: ΔB=1.5(5) G.
- The asymmetric Fano line shape of the interspecies elastic cross section was experimentally observed.
Conclusions:
- The developed model provides a tool for selecting optimal Feshbach resonances in atomic mixtures.
- The experimental results validate the model and provide crucial parameters for future studies.
- The 6Li/40K system shows promise for investigating universal crossover physics due to its mass imbalance and controllable interactions.
Related Concept Videos
01:13¹H NMR: Complex Splitting
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied first.
01:08Spin–Spin Coupling Constant: Overview
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
01:23IR Spectrum Peak Broadening: Hydrogen Bonding
The vibrational frequency of a bond is directly proportional to its bond strength. As a result, stronger bonds vibrate at higher frequencies, while weaker bonds vibrate at lower frequencies. The stretching vibration of the strong O–H bond in alcohols and phenols (very dilute solution or gas phase) appears as a sharp peak at 3600–3650 cm−1.
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
However, the extent of hydrogen bonding influences the observed stretching frequency and band broadening. Intermolecular or intramolecular hydrogen bonding...
01:04¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
01:27¹H NMR: Long-Range Coupling
The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
03:51Molecular Orbital Theory II
Molecular Orbital Energy Diagrams