Modification of spontaneous emission and local-field effects in dielectrics

Summary form only given.To determine the refractivity in situ, a time-resolved interferometric technique is used. The technique is based on cross correlating a reference pulse and a transmitted pulse from a 70-fs Ti:sapphire laser with the use of a commercially available Fourier-transform spectrometer. This approach enables us to obtain the pulse delay through the dense gas with 10-fs resolution in the refractive-index change. The resulting molecule Eu(fod), is optically excited with a pulsed, tripled Nd:YAG laser at 355 nm, and luminescence is detected in the red (614 nm). Radiative decay rates are in the convenient ms range and are recorded with a multichannel scaler. We present measurements on the radiative lifetime of Eu (fod), in supercritical CO/sub 2/ with varying refractive index. Different local field models are discussed.