A theoretical study of the dynamics of paramagnetic superrotors in external magnetic fields

Floß, Johannes

doi:10.1088/0953-4075/48/16/164005

Cited by 7 publications

(11 citation statements)

References 51 publications

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“…Note that using Ω N,+1 = Ω N,−1 ≡ Ω N = µ B gB/( N ) in accord with Eq.2 did not produce satisfactory fits, owing to the partial decoupling of S from N at high values of magnetic field [22]. To account for this effect, we numerically diagonalized the spin-rotational Hamiltonian in the presence of an external magnetic field:…”

Section: Transverse Magnetizationmentioning

confidence: 99%

“…To study the induced magnetization further, we applied an external magnetic field along the vertical (ẑ) axis. In a recent study of the dynamics of paramagnetic oxygen super-rotors in an external magnetic field [21][22][23], it was found that the spin-rotation coupling serves as an efficient mediator between the applied B-field and the molecular rotation, enabling magnetic control of the rotational degree of freedom. Here, we demonstrate the effect of SR coupling on the centrifuge-induced magnetization.…”

Section: Non-zero External Fieldmentioning

confidence: 99%

“…It reaches 0.65µ B per every centrifuged molecule and creates a local magnetic flux density B ⊥ = µ 0 M ⊥ of almost 40 mG in the gas under the pressure of half atmosphere (here, µ 0 is the vacuum permeability). Such large value of M ⊥ can be understood by analyzing the rotational dynamics of paramagnetic super-rotors in an external magnetic field [21,22]. An optical centrifuge drives the molecules to a state of high angular momentum N, while an applied magnetic field generates a torque on the electronic spin S. If the field is not strong enough to decouple the two vectors (in the case of oxygen, of order of 1 T or below), SR interaction causes the angular momentum to precess together with S. The precession frequency depends on the mutual orientation of N and S in the following way [22]:…”

Section: Transverse Magnetizationmentioning

confidence: 99%

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Ultrafast Magnetization of a Dense Molecular Gas with an Optical Centrifuge

2017

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Strong laser-induced magnetization of oxygen gas at room temperature and atmospheric pressure is achieved experimentally on the sub-nanosecond time scale. The method is based on controlling the electronic spin of paramagnetic molecules by means of manipulating their rotation with an optical centrifuge. Spin-rotational coupling results in high degree of spin polarization on the order of one Bohr magneton per centrifuged molecule. Owing to the non-resonant interaction with the laser pulses, the demonstrated technique is applicable to a broad class of paramagnetic rotors. Executed in a high-density gas, it may offer an efficient way of generating macroscopic magnetic fields remotely (as shown in this work), producing large amount of polarized electrons and converting electronic to nuclear spin polarization.

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Section: Transverse Magnetizationmentioning

confidence: 99%

Section: Non-zero External Fieldmentioning

confidence: 99%

Section: Transverse Magnetizationmentioning

confidence: 99%

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Ultrafast Magnetization of a Dense Molecular Gas with an Optical Centrifuge

2017

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“…Using J S, we approximated the angular distribution of the state |N, S, J, M J by the spherical harmonics Y J,M J (θ, φ). This approximation was verified by a more elaborate calculation of the exact angular distributions [31]. Using this approximation, the final angular distribution at time t is given as:…”

Section: Magneto-optical Properties Of Paramagnetic Super Rotorsmentioning

confidence: 84%

“…Consider a Hund's case (b) molecule possessing an electronic spin, such as molecular oxygen 16 O 2 in the ground electronic state. Its electronic spin is strongly coupled to the molecular angular momentum N. In an external magnetic field, sufficiently weak for not causing the spin to decouple from N, the angular momentum will precess with frequency [31]…”

Section: Dynamics Of Super Rotors In External Magnetic Fieldsmentioning

confidence: 99%

Control of molecular rotation with an optical centrifuge

Korobenko

2018

J. Phys. B: At. Mol. Opt. Phys.

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Dynamics of molecular superrotors in an external magnetic field

Korobenko

Milner

2015

J. Phys. B: At. Mol. Opt. Phys.

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We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to the qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin-rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane in three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation. PACS numbers:Magnetic field is one of the most powerful tools for controlling atomic and molecular dynamics. Both translational and rotational degrees of freedom of molecules have been successfully manipulated via various types of magnetic interaction. Alignment of molecular axes has been accomplished by creating pendular states in paramagnetic molecules at low temperature [1,2]. Gyroscopic precession along the direction of the applied magnetic field has been suggested for non-magnetic molecules in dispersionless "cogwheel" states [3,4]. Spin-rotational coupling has been recently utilized for converting unidirectional molecular rotation into axial alignment, manifested through magneto-rotational optical birefringence under ambient conditions [5,6].Recent progress in creating and detecting unidirectional rotation of molecules [7][8][9][10][11]18] revived the interest in controlling molecular rotation with external magnetic fields. Magnetic effects could further broaden the controllability provided by tunable rotational excitation, including control of molecular collisions [12,13] and scattering of molecules at gas-solid interfaces [14], molecular trajectories [15] and formation of gas vortices [16], optical [5, 17] and acoustic [19,20] properties of a gas of rotating molecules.With the invention of the optical centrifuge technique [21,22], a very flexible control over the degree of rotational excitation became available. The technique proved capable of producing synchronously rotating molecules with narrow rotational state distribution in a wide variety of species up to extremely high angular frequencies [5,23]. However, the spatial orientation of the induced angular momentum is often defined by the propagation direction of the excitation laser beam, and is therefore not easy to manipulate.Here we demonstrate how an applied magnetic field can be used to rotate the plane of molecular rotation. The described method is applicable to a wide variety of molecules and relies on the coupling between the rotation of a molecule and its magnetic moment. An applied magnetic field causes this moment to precess, "...

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A theoretical study of the dynamics of paramagnetic superrotors in external magnetic fields

Cited by 7 publications

References 51 publications

Ultrafast Magnetization of a Dense Molecular Gas with an Optical Centrifuge

Ultrafast Magnetization of a Dense Molecular Gas with an Optical Centrifuge

Control of molecular rotation with an optical centrifuge

Dynamics of molecular superrotors in an external magnetic field

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