Quantum and Classical Fall of a Charged Particle onto a Stationary Dipolar Target

The quantum dynamics of the fall of a charged particle (i.e., the capture of a charged particle) onto a stationary dipolar target is considered. Extending previous approaches for the calculation of rate coefficients in the lowest channels, we now determine rate coefficients for all channels until the quantum rate coefficients converge to their classical counterpart. The results bridge the gap between the capture of light particles (electrons) and heavy particles (ions) in the limit of sudden dynamics, when the collision time is short in comparison to the rotational period of the molecular target. The quantum-classical correspondence is discussed in terms of semiclassical numbers or channels which are open for capture in effective potentials formed by charge-dipole attraction and centrifugal repulsion. The quantum capture rate coefficients are presented through classical rate coefficients and correction factors that converge to unity for high temperatures and whose behavior at ultralow temperatures, for not too small values of the dipole moment, is determined by semiclassical numbers of capture channels.