Related Experiment Video
Updated: Jul 11, 2026
10:40
High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Single molecule electron paramagnetic resonance spectroscopy: hyperfine splitting owing to a single nucleus
Science (New York, N.Y.)
|June 9, 1995
Summary
Researchers studied pentacene molecules in a p-terphenyl host using optically detected electron paramagnetic resonance. They observed magnetic resonance transitions and hyperfine interactions with carbon-13 nuclei in the pentacene molecules.
Area of Science:
- Solid-state physics and spectroscopy.
- Molecular magnetism and quantum chemistry.
Background:
- Pentacene is a polycyclic aromatic hydrocarbon with potential applications in organic electronics.
- Understanding molecular spin dynamics is crucial for developing new quantum technologies.
- Electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for probing unpaired electron spins.
Purpose of the Study:
- To investigate the triplet sublevels of individual pentacene-d(14) molecules doped in a p-terphenyl-d(14) host crystal.
- To analyze the magnetic resonance transitions and hyperfine interactions within these molecules.
- To elucidate the role of carbon-13 nuclei in influencing the spin properties of pentacene.
Main Methods:
- Optically detected electron paramagnetic resonance (OD-EPR) spectroscopy.
- Doping individual pentacene-d(14) molecules into a p-terphenyl-d(14) host crystal.
- Applying an external magnetic field to observe resonance transitions.
Main Results:
- Observed magnetic resonance transitions between the triplet sublevels of pentacene.
- Detected splitting of resonance lines due to the presence of a carbon-13 nucleus.
- Attributed the observed splitting to the hyperfine interaction between the triplet electron spin and the carbon-13 nuclear spin.
Conclusions:
- The study successfully characterized the spin properties of individual pentacene molecules using OD-EPR.
- The hyperfine interaction with carbon-13 nuclei was confirmed as a significant factor influencing pentacene's magnetic resonance.
- These findings contribute to the fundamental understanding of spin dynamics in organic molecular systems.
More Related Videos
Related Concept Videos
01:17Electron Paramagnetic Resonance (EPR) Spectroscopy: Organic Radicals
Ideally, an unpaired electron shows a single peak in the EPR spectrum due to the transition between the two spin energy states. However, coupling interactions can occur between the spins of the unpaired electron and any neighboring spin-active nuclei. This hyperfine coupling results in hyperfine splitting, where the EPR signal is split into multiplets. The signals split into 2nI + 1 peaks, where n is the number of equivalent nuclei and I is the nuclear spin. These splitting patterns provide...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
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...
01:13¹H 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.
01:13¹H NMR Signal Multiplicity: Splitting Patterns
When protons A and X are coupled, their nuclear spin energy levels are slightly modified. This is because the energy required to excite proton A to a spin state parallel to proton X is slightly different from the energy required for it to become anti-parallel to spin X. Consequently, there are two possible excitation frequencies for A (A1 and A2), depending on the spin state of X, and vice versa. The mutual nature of coupling implies that the difference between frequencies A1 and A2, indicated...
01:05Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...