Vibrational Fluorescence of CN−Defects in KCl Excited by Coupling to Optically PumpedFCenters

Vibrational emission from molecular defects in ionic crystals has been observed for the first time, realized by dilute C${\mathrm{N}}^{-}$ defects in KCl which emit a long-lifetime fluorescence at 4.8 μm. After association of $F$ centers to the C${\mathrm{N}}^{-}$ defects, the emission can be pumped efficiently by optical $F$-center excitation through electronic-vibrational coupling. This coupling is confirmed through Raman experiments. Relative intensity, emission spectra, and lifetime data as a function of crystal temperature are reported for the 4.8μm emission.