Related Experiment Video
Updated: May 10, 2026
11:43
Hyperpolarized 13C Metabolic Magnetic Resonance Spectroscopy and Imaging
Published on: December 30, 2016
Parahydrogen-induced polarization at zero magnetic field
Mark C Butler1, Gwendal Kervern, Thomas Theis
1Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. mrkcbutler@gmail.com
The Journal of Chemical Physics
|June 28, 2013
Summary
This study demonstrates converting parahydrogen
Area of Science:
- Quantum Chemistry
- Nuclear Magnetic Resonance Spectroscopy
Background:
- Parahydrogen is a spin isomer of dihydrogen.
- The singlet state of parahydrogen can be converted into detectable signals under specific conditions.
Purpose of the Study:
- To describe the conversion of parahydrogen's singlet state into oscillating sample magnetization.
- To analyze the role of scalar coupling and pulsed magnetic fields in this conversion process.
Main Methods:
- Symmetry arguments and simple model systems were employed.
- Analysis involved scalar-coupling Hamiltonian and pulsed magnetic field sequences.
- Single-transition operators were used for analytical description.
Main Results:
- The singlet state evolves into scalar spin order.
- A dc pulse converts scalar order into vector order, maximal at specific rotation angles.
- Vector order oscillates and leads to detectable molecular spin dipole oscillations.
Conclusions:
- The described method allows for the generation of oscillating magnetization from parahydrogen's singlet state.
- The process relies on the interplay between scalar coupling and pulsed field manipulation.
- This technique offers a pathway for enhanced NMR signal generation.
Related Concept Videos
01:30Paramagnetism
Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...
01:28Induced Electric Dipoles
A permanent electric dipole orients itself along an external electric field. This rotation can be quantified by defining the potential energy because the external torque does work in rotating it. Then, the potential energy is minimum at the parallel configuration and maximum at the antiparallel configuration. While the former is a stable equilibrium, the latter is an unstable equilibrium.
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:24Potential Due to a Magnetized Object
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
The vector...
00:59Atomic Nuclei: Nuclear Magnetic Moment
All atomic nuclei are positively charged. When they have a nonzero spin, they behave like rotating charges. As a consequence of their charge and spin, these nuclei generate a magnetic field (B). This, in turn, gives rise to a magnetic moment (μ), which is randomly oriented in the absence of an external magnetic field. When an external magnetic field (B0) is applied, the magnetic moment vectors can align with the field or against it in 2 + 1 orientations. A hydrogen nucleus, which is just a...
01:31Ferromagnetism
Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...