FEMTOSECOND PHOTOLYSIS OF KCL WITH 6EV PHOTONS

We have measured transient absorption spectra following creation of el ectron-hole pairs by 600fs pulses in the 5.7-6eV photon energy range i n potassium chloride. This is the highest excitation photon energy yet used in sub-picosecond absorption spectroscopy of defect formation in insulators. It allows two-photon excitation of electron-hole pairs in materials including the alkaline earth fluorides. Compared to previou s studies on familiar samples such as KCl and KBr, a different distrib ution of electron-hole pair states is populated initially, and the exc itation pulse interacts with a different spectrum of early photo-induc ed transient absorption.