Time- and Energy-Resolved Luminescence of the XeKr Exciplex

The emission spectrum of the XeKr exciplex was recorded by selectively exciting the first atomic resonance of xenon doped into liquid and solid krypton. A single emission band, centred at 7.87 eV, was observed in the liquid. In the solid the emission spectrum is time dependent. For longer times (t25 ns) after excitation it is almost identical to the one obtained in the liquid. At shorter times an additional band peaked at ~ 8.30 eV is superimposed. For the first time, the radiative lifetime of the 1(3P2) exciplex could be determined. Its value is (52 ± 3) and (50 ± 3) ns in the liquid and the solid, respectively. The corresponding value for the dilute gas is estimated to be 140 ns.