Optical Quenching of Metastable Helium Atoms using Excitation to the $4P$ State

Abstract

Discharge and electron-impact excitation lead to the production of metastable helium atoms in two metastable states, 2${}^1$S${}_0$ and 2${}^3$S${}_1$. However, many applications require pure beams of one of these species or at least a detailed knowledge of the relative state populations. In this paper, we present the characterization of an original experimental scheme for the optical depletion of He(2${}^1$S${}_0$) in a supersonic beam which is based on the optical excitation of the 4${}^1$P${}_1\leftarrow 2^1$S${}_0$ transition at 397 nm using a diode laser. From our experimental results and from a comparison with numerical calculations, we infer a near unit depletion efficiency at all beam velocities under study (1070 m/s $\le v\le$ 1750 m/s). Since the technique provides a direct means to determine the singlet-to-triplet ratio in a pulsed supersonic helium beam, our results show that the intrabeam singlet-to-triplet ratio is different at the trailing edges of the gas pulse.

References in corpus (6)

• Observation of Quantum Effects in sub Kelvin Cold Reactions
• Cold and trapped metastable noble gases
• Energy dependent stereodynamics of the Ne(${}^3$P${}_2$)+Ar reaction
• Zeeman deceleration of electron-impact-excited metastable helium atoms
• Production of rotationally cold methyl radicals in pulsed supersonic beams
• Penning collisions between supersonically expanded metastable helium atoms and laser-cooled lithium atoms

Cited by in corpus (5)

• Pauli blocking of stimulated emission in a degenerate Fermi gas
• Suppression of Penning ionization by orbital angular momentum conservation
• Single-Source, Collinear Merged-Beam Experiment for the Study of Reactive Neutral-Neutral Collisions
• Preparation of individual magnetic sub-levels of ${}^4$He($2^3$S${}_1$) in a supersonic beam using laser optical pumping and magnetic hexapole focusing
• Spin-state-controlled chemi-ionization reactions between metastable helium atoms and ground-state lithium atoms