Time-dependent polarization transfer from molecular rotation to nuclear spin

Abstract

It has been proposed recently that hyperfine depolarization of selected molecular rotational states can be used to produce molecules with highly polarized nuclear spins, and formulas for two distinct nuclei have been given in the limit of hierarchical approximation. Here we present the general, nonhierarchical coupling formalism for the derivation of the H ͓i͔ ͑k͒ ͑I , t͒ factors that govern the time dependence of the nuclear polarizations.The described technique, especially when combined with methods that polarize the electronic angular momentum, can lead to the production of highly polarized atoms from molecular photodissociation, at densities close to that of the parent molecule. In addition, we calculate the time dependence of the H and F nuclear spin polarizations, following the pulsed-laser preparation of the HF ͑v =1,J =1,m =1͒ state. It is shown that the polarization of the F and H nuclear spins attain values of about 85% and 70% at time delays of about 1 s and 4 s, respectively. Similar results are shown for the pulsed preparation of the DF ͑v =0,J =1,m =1͒ state, demonstrating the D atoms can also be significantly polarized.

Nuclear hyperpolarization in solids and the prospects for nuclear spintronics

“…PHIP is just one example of an emerging class of methods that exploit the selection of vibrational or rotational states in the gas phase, which in turn provide pure nuclear spin states. Both HF and HCl molecules have been prepared recently in highly athermal nuclear spin states via laser excitation of specific vibrational and rotational lines [15,16].…”

Elastic depolarization and polarization transfer in CN(A2Π,v= 4)+Ar collisions

“…In principle, however, the nuclear spin is no longer isotropic, as the initial depolarization of j will have resulted in a corresponding (time-varying, with defined average) alignment of I. 76 However, given the relative magnitudes of j and I, the magnitude of the alignment stored in the nuclear spin is low for j = 6.5. We calculate the time-averaged nuclear alignment generated to be only ≈ 1% of the initial rotational alignment for j = 6.5.…”

Nanosecond control and high-density production of spin-polarized hydrogen atoms

“…19,20,21 The sum and difference profiles of HBr were analyzed using equations 2a and 2b, and the values of P Z and P X are plotted in Fig 2c, along with quantum mechanical ab initio calculated values, 22 and predictions using conservation of angular momentum from previous measurements of the Br cofragments. 15 The values of P Z and P X correspond to the nascent electron polarizations, whereas the proton polarization is initially unpolarized; after 0.7 ns, the polarization is shared between the electron and the proton, and the long-time average polarizations for both the electron and proton are half the values shown in Fig 2c. However, methods have been proposed to polarize the proton before photodissociation, so that the final SPH polarization values need not be reduced, 23 or the electron polarization can be maintained using a magnetic field greater than about 100mT, 11 without being depolarized by the proton.…”