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Register a new userHunds paradox and the collisional stabilization of chiral molecules
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We identify the dominant collisional decoherence mechanism which serves to stabilize and super-select the configuration states of chiral molecules. A high-energy description of this effect is compared to the results of the exact molecular scattering problem, obtained by solving the coupled-channel equations. It allows to predict the experimental conditions for observing the collisional suppression of the tunneling dynamics between the left-handed and the right-handed configuration of D2S2 molecules.
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We propose a novel type of Rydberg dimer, consisting of a Rydberg-state atom bound to a distant positive ion. The molecule is formed through long-range electric-multipole interaction between the Rydberg atom and the point-like ion. We present potential energy curves (PECs) that are asymptotically connected with Rydberg $nP$- or $nD$-states of rubidium or cesium. The PECs exhibit deep, long-range wells which support many vibrational states of Rydberg-atom-ion molecules (RAIMs). We consider photo-association of RAIMs in both the weak and the strong optical-coupling regimes between initial and Rydberg states of the neutral atom. Experimental considerations for the realization of RAIMs are discussed.
A strong inhomogeneous static electric field is used to spatially disperse a rotationally cold supersonic beam of 2,6-difluoroiodobenzene molecules according to their rotational quantum state. The molecules in the lowest lying rotational states are selected and used as targets for 3-dimensional alignment and orientation. The alignment is induced in the adiabatic regime with an elliptically polarized, intense laser pulse and the orientation is induced by the combined action of the laser pulse and a weak static electric field. We show that the degree of 3-dimensional alignment and orientation is strongly enhanced when rotationally state-selected molecules, rather than molecules in the original molecular beam, are used as targets.
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We investigate the linear behavior in the 2+ ion concentration observed in the double photoionization of a variety of aromatic molecules. We show it arises when the photoelectrons are emitted simultaneously. Neglecting the momentum of the incoming photon and the momentum transferred to the molecule, it follows that the momenta of the individual photoelectrons are oppositely directed and equal in magnitude. Under steady-state conditions, the ion concentration is proportional to the rate at which the ions are created which, in turn, varies as the product of the densities of states of the individual electrons. The latter vary as the square root of the kinetic energy, leading to overall linear behavior. The origin of the linear behavior in pyrrole and related molecules is attributed to the presence of atoms that destroy the periodicity of a hypothetical carbon loop. In contrast, the resonant behavior observed in pyridine and related molecules, where a fraction of the CH pairs is replaced by N atoms, is associated with electron transfer between the nitrogen atoms and carbon atoms that preserves the periodicity of the closed loop.
The BOUND program calculates the bound states of a complex formed from two interacting particles using coupled-channel methods. It is particularly suitable for the bound states of atom-molecule and molecule-molecule Van der Waals complexes and for the near-threshold bound states that are important in ultracold physics. It uses a basis set for all degrees of freedom except $R$, the separation of the centres of mass of the two particles. The Schrodinger equation is expressed as a set of coupled equations in $R$. Solutions of the coupled equations are propagated outwards from the classically forbidden region at short range and inwards from the classically forbidden region at long range, and matched at a point in the central region. Built-in coupling cases include atom + rigid linear molecule, atom + vibrating diatom, atom + rigid symmetric top, atom + asymmetric or spherical top, rigid diatom + rigid diatom, and rigid diatom + asymmetric top. Both programs provide an interface for plug-in routines to specify coupling cases (Hamiltonians and basis sets) that are not built in. With appropriate plug-in routines, BOUND can take account of the effects of external electric, magnetic and electromagnetic fields, locating bound-state energies at fixed values of the fields. The related program FIELD uses the same plug-in routines and locates values of the fields where bound states exist at a specified energy. As a special case, it can locate values of the external field where bound states cross scattering thresholds and produce zero-energy Feshbach resonances. Plug-in routines are supplied to handle the bound states of a pair of alkali-metal atoms with hyperfine structure in an applied magnetic field.
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