Production of Metastable Hg Atoms by Charge Exchange

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Abstract
Neutral mercury atoms, formed by charge exchange processes between positive mercury ions and mercury vapor atoms, were found to liberate a copious yield of secondary electrons from a metal surface. Values of γ as high as 0.40 were observed. The source of positive ions was the plasma of a mercury arc discharge. Since such a high yield of secondary electrons is not indicative of ground state neutral atoms, the atoms were assumed to be metastable. To test this hypothesis the neutrals were allowed to decay in their flight to the target. A second method of quenching the supposed metastable atoms consisted of admitting minute quantities of H2 and Ar gas into their flight path. In both cases the secondary emission was reduced by several orders of magnitude thus verifying the metastability hypothesis. The 4.66‐, 5.43‐, and 9.0‐eV metastable states were observed along with a long‐lived state having a mean lifetime of 6.0 μsec. As an experimental side light of great importance, it was observed that Hg− ions were formed in the collimated beam of excited neutral atoms.