Experimental evidence of twin fast metastable H(2S) atoms from dissociation of cold H_2 induced by electrons

TL;DR

This study provides direct experimental evidence of the simultaneous formation of two metastable H(2S) atoms from cold H_2 dissociation induced by electron impact, confirming a previously unobserved dissociation channel.

Contribution

First direct detection and coincidence measurement of twin H(2S) atoms from cold H_2 dissociation induced by electrons, revealing a new dissociation pathway.

Findings

Confirmed the H(2S)-H(2S) dissociation channel.

Demonstrated the use of localized quenching and Lyman-lpha detection.

Provided evidence for a new molecular dissociation process.

Abstract

We report the direct detection of two metastable H(2S) atoms coming from the dissociation of a single cold H_2 molecule, in coincidence measurements. The molecular dissociation was induced by electron impact in order to avoid limitations by the selection rules governing radiative transitions. Two detectors, placed close from the collision center, measure the neutral metastable H(2S) through a localized quenching process, which mixes the H(2S) state with the H(2P), leading to a Lyman-\alpha detection. Our data show the accomplishment of a coincidence measurement which proves for the first time the existence of the H(2S)-H(2S) dissociation channel.