Alignment of ND3 molecules in dc-electric fields

The control of movement and orientation of gas-phase molecules has become the focus of many research areas in molecular physics. Here, ND3 molecules are polarized in a segmented, curved electrostatic guide and adiabatically aligned inside a rotatable mass spectrometer (MS). Alignment is probed by photoionization using a linearly polarized laser. Rotation of the polarization at fixed MS orientation has the same effect as the rotation of the MS at fixed polarization, proving that the molecular alignment adiabatically follows the MS axis. Polarization-dependent ion signals reveal state-specific populations and allow for a quantification of the aligned sample in the space-fixed reference frame.

Electronic and dynamical properties of non-covalent diatomic aggregates formed by He with neutral and ionic Li and Be

CONTEXT AND RESULTS

This work aims to study the influence of the absence and presence of permanent charges on the electronic and dynamical properties of the non-covalent bound diatomic systems involving He and Li, Be as neutral and ionic partners. The charge displacement results suggest that in the formation of HeLi[Formula: see text], HeBe[Formula: see text], and HeBe[Formula: see text], the neutral He atom undergoes, in the electric field of the ion, a pronounced electronic polarization, and the natural bond order theoretical approach indicates that in the formation of the molecular orbital He acts as a weak electron donor. The energy decomposition analysis provides the dispersion and induction components as the attractive leading terms controlling the stability of all systems, confirming that the formed bond substantially maintains a non-covalent nature which is also supported by the Quantum Theory of Atoms in Molecules (QTAIM) analysis. Finally, it was found that the HeLi and HeBe neutral systems are unstable under any condition, HeLi[Formula: see text] and HeBe[Formula: see text] ionic systems are stable below 317K and 138K, respectively, while the HeBe[Formula: see text] system becomes unstable only after 3045K.

COMPUTATIONAL AND THEORETICAL TECHNIQUES

The potential energy curves and interactions in all systems were studied theoretically based on coupled-cluster singles and doubles method with perturbative inclusion of triples CCSD(T) method with an aug-cc-pV5Z basis set. More precisely, it was determined the potential energy curves describing the stability of the HeLi, HeLi[Formula: see text], HeBe, HeBe[Formula: see text], and HeBe[Formula: see text] systems, the charge displacement within the formed adducts, the decomposition of their total interaction energy, the topological analysis of their bonds, their rovibrational energies, their spectroscopic constants and lifetimes.

Prediction of a Feshbach Resonance in the Below-the-Barrier Reactive Scattering of Vibrationally Excited HD with H

Quantum reactive scattering calculations on the vibrational quenching of HD due to collisions with H were carried out employing an accurate potential energy surface. The state-to-state cross sections for the chemical reaction HD(v = 1, j = 0) + H → D + H₂(v' = 0, j') at collision energies between 1 and 10 000 cm^-1 are presented, and a Feshbach resonance in the low-energy regime, below the reaction barrier, is observed for the first time. The resonance is attributed to coupling with the vibrationally adiabatic potential correlating to the v = 1, j = 1 level of the HD molecule, and it is dominated by the contribution from a single partial wave. The properties of the resonance, such as its dynamic behavior, phase behavior, and lifetime, are discussed.