  We demonstrate the generation of metastable krypton in the long-lived 1s5
state using laser excitation. The atoms are excited through a two-photon
absorption process into the 2p6 state using a pulsed optical parametric
oscillator laser operating near 215 nm, after which the atoms decay quickly
into the metastable state with a branching ratio of 75 %. The interaction
dynamics are modeled using density matrix formalism and, by combining this with
experimental observations, we are able to calculate photo-ionization and
two-photon absorption cross-sections. When compared to traditional approaches
to metastable production, this new approach shows great potential for
high-density metastable krypton production with minimal heating of the sample.
Here, we show metastable production efficiencies of up to 2% per pulse. The new
experimental results gained here, when combined with the density matrix model
we have developed, suggest that fractional efficiencies up to 30% are possible
under optimal conditions.
