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Register a new userDynamics of OH(2Pi)-He collisions in combined electric and magnetic fields
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We use accurate quantum mechanical calculations to analyze the effects of parallel electric and magnetic fields on collision dynamics of OH(2Pi) molecules. It is demonstrated that spin relaxation in 3He-OH collisions at temperatures below 0.01 K can be effectively suppressed by moderate electric fields of order 10 kV/cm. We show that electric fields can be used to manipulate Feshbach resonances in collisions of cold molecules. Our results can be verified in experiments with OH molecules in Stark decelerated molecular beams and electromagnetic traps.
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The stereochemical properties of the ultracold ground state OH molecule in the presence of electric and magnetic fields are currently of considerable interest. For example, relevant quantities such as molecular alignment and orientation, calculated numerically by using large basis sets, have lately appeared in the literature. In this work, based on our recent exact solution to an effective eight-dimensional matrix Hamiltonian for the molecular ground state, we present analytic expressions for the stereochemical properties of OH. Our results require the solution of algebraic equations only, agree well with the aforementioned fully numerical calculations, provide compact expressions for simple field geometries, allow ready access to relatively unexplored parameter space, and yield straightforwardly higher moments of the molecular axis distribution.
The OH molecule is currently of great interest from the perspective of ultracold chemistry, quantum fluids, precision measurement and quantum computation. Crucial to these applications are the slowing, guiding, confinement and state control of OH, using electric and magnetic fields. In this article, we show that the corresponding eight-dimensional effective ground state Stark-Zeeman Hamiltonian is exactly solvable and explicitly identify the underlying chiral symmetry. Our analytical solution opens the way to insightful characterization of the magnetoelectrostatic manipulation of ground state OH. Based on our results, we also discuss a possible application to the quantum simulation of an imbalanced Ising magnet.
We present detailed calculations on resonances in rotationally and spin-orbit inelastic scattering of OH ($X,^2Pi, j=3/2, F_1, f$) radicals with He and Ne atoms. We calculate new emph{ab initio} potential energy surfaces for OH-He, and the cross sections derived from these surfaces compare favorably with the recent crossed beam scattering experiment of Kirste emph{et al.} [Phys. Rev. A textbf{82}, 042717 (2010)]. We identify both shape and Feshbach resonances in the integral and differential state-to-state scattering cross sections, and we discuss the prospects for experimentally observing scattering resonances using Stark decelerated beams of OH radicals.
We present an experimental study on the rotational inelastic scattering of OH ($X^2Pi_{3/2}, J=3/2, f$) radicals with He and D$_2$ at collision energies between 100 and 500 cm$^{-1}$ in a crossed beam experiment. The OH radicals are state selected and velocity tuned using a Stark decelerator. Relative parity-resolved state-to-state inelastic scattering cross sections are accurately determined. These experiments complement recent low-energy collision studies between trapped OH radicals and beams of He and D$_2$ that are sensitive to the total (elastic and inelastic) cross sections (Sawyer emph{et al.}, emph{Phys. Rev. Lett.} textbf{2008}, emph{101}, 203203), but for which the measured cross sections could not be reproduced by theoretical calculations (Pavlovic emph{et al.}, emph{J. Phys. Chem. A} textbf{2009}, emph{113}, 14670). For the OH-He system, our experiments validate the inelastic cross sections determined from rigorous quantum calculations.
We report on the observation of magnetic dipole allowed transitions in the well-characterized $A,^2Sigma^+ - X,^2Pi$ band system of the OH radical. A Stark decelerator in combination with microwave Rabi spectroscopy is used to control the populations in selected hyperfine levels of both $Lambda$-doublet components of the $X,^2Pi_{3/2},v=0,J=3/2$ ground state. Theoretical calculations presented in this paper predict that the magnetic dipole transitions in the $ u=1 leftarrow u=0$ band are weaker than the electric dipole transitions by a factor of $2.58times 10^3$ only, i.e., much less than commonly believed. Our experimental data confirm this prediction.
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