Theoretical investigation of the autoionization process in molecular collision complexes: He*(2 3S)+Li(2 2S)→He+Li++e−

Abstract

A complete ab initio treatment is applied to the autoionization process in the He*(2s 3S)+Li(2s 2S) collisional complex. Feshbach projection based on orbital occupancy, implemented in a multireference configuration interaction (MRCI) code, defines the resonance state and provides the entrance channel potential curve as well as all pertinent information on the resonance–continuum coupling. The l-dependent coupling elements in local approximation are obtained by projecting a compact one-electron function, named Penning molecular orbital (PMO), onto the wave function of the ejected electron with proper energy. The continuum wave function is obtained by coupled channel calculations in the static-exchange approximation. A converged set of seven complex coupling matrix elements, used in the nuclear dynamics calculation based on a complex Numerov algorithm, fully describes the electron angular momentum transfer. The calculated angle-dependent spectra, as well as the total, angle-, and energy-integrated ionization cross sections agree well with available experimental data.

Penning collisions between supersonically expanded metastable He atoms and laser-cooled Li atoms

“…The experimental setup comprises a MOT for ultracold 7 Li atoms and a supersonic beam source for metastable helium atoms. A schematic drawing of the apparatus is shown in Figure 1.…”

“…A high-density cloud of ultracold 7 Li atoms (≈ 10 9 atoms, 3.8 mm FWHM diameter) is continuously produced using laser cooling and magneto-optical trapping. For this, an effusive beam of Li atoms is produced in an oven (T = 693 K) and decelerated in a decreasing-field Zeeman slower 37 .…”

“…More accurate experimental data for this reaction system will thus aid the theoretical description of potential energy surfaces and the associated quantum dynamics calculations. With a total of only five electrons involved, He*-Li represents a collision system especially suitable for accurate quantum-chemical calculations 6,7 .…”

Coherent Control of Penning and Associative Ionization: Insights from Symmetries

“…Consider as an example PI of metastable Helium and Lithium [28,29] (the AI cross section is here ignorable since HeLi + is very weakly bound):…”

An ultracold, optically trapped mixture of 87Rb and metastable 4He atoms

“…Accurate ab initio calculations of the quartet 4 Σ + potentials and the corresponding quartet scattering lengths have recently become available for Li, K, Na and Rb [49], and while most of the doublet 2 Σ + potentials have been studied experimentally and theoretically in the past (see e.g. [50][51][52][53][54]), the doublet scattering lengths are unknown. Importantly, the large internal energy of 19.8 eV of He * leads to Penning ionization (PI):…”