Direct Observation of a Feshbach-resonance by Coincidence-detection of Ions and Electrons in Penning Ionization Collisions

Abstract

Observation of molecular dynamics with quantum state resolution is one of the major challenges in chemical physics. Complete characterization of collision dynamics leads to the microscopic understanding and unraveling of different quantum phenomena such as scattering resonances. We present a new experimental approach for observing molecular dynamics involving neutral particles and ions that is capable in providing state-to-state mapping of the dynamics. We use Penning ionization reaction between argon and metastable helium to generate argon ion and ground state helium atom pairs at separation of several angstroms. The energy of ejected electron carries the information about the initial electronic state of an ion. The coincidence detection of ionic products provides a state resolved description of the post-ionization ion-neutral dynamics. We demonstrate that correlation between the electron and ion energy spectra enables us to directly observe the spin-orbit excited Feshbach resonance state of HeAr${}^{+}$. We measure the lifetime of the quasi-bound HeAr${}^{+}$ A${}_2$ state and discuss possible applications of our method.

References in corpus (10)

• Observation of Quantum Effects in sub Kelvin Cold Reactions
• Observation of the Efimov state of the helium trimer
• Millikelvin Reactive Collisions between Sympathetically-Cooled Molecular Ions and Laser-Cooled Atoms in an Ion-Atom Hybrid Trap
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• Observation of correlated excitations in bimolecular collisions
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• Phase protection of Fano-Feshbach resonances

Cited by in corpus (4)

• Determining the nature of quantum resonances by probing elastic and reactive scattering in cold collisions
• Tomography of Feshbach Resonance States
• Quantum state resolved molecular dipolar collisions over four decades of energy
• Observation of the P-wave Shape Resonance