Control and imaging of O(1D2) precession

Abstract

Larmor precession of a quantum mechanical angular momentum vector about an applied magnetic field forms the basis for a range of magnetic resonance techniques, including nuclear magnetic resonance spectroscopy and magnetic resonance imaging. We have used a polarized laser pump–probe scheme with velocity-map imaging detection to visualize, for the first time, the precessional motion of a quantum mechanical angular momentum vector. Photodissociation of O2 at 157 nm provides a clean source of fast-moving O(1D2) atoms, with their electronic angular momentum vector strongly aligned perpendicular to the recoil direction. In the presence of an external magnetic field, the distribution of atomic angular momenta precesses about the field direction, and polarization-sensitive images of the atomic scattering distribution recorded as a function of field strength yield ‘time-lapse-photography’ style movies of the precessional motion. We present movies recorded in various experimental geometries, and discuss potential consequences and applications in atmospheric chemistry and reaction dynamics. Larmor precession of a quantum mechanical angular momentum vector about an applied magnetic field forms the basis for NMR spectroscopy, MRI and a range of other important analytical techniques. This precessional motion has now been imaged for the first time, using velocity-map imaging in a model system of strongly polarized oxygen atoms.

Cite this article

Wu, SM., Radenovic, D., van der Zande, W. et al. Control and imaging of O(¹D₂) precession. Nature Chem 3, 28–33 (2011). https://doi.org/10.1038/nchem.929

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